Add read lock to task string method

[mye956]

Summary

This PR will add a read lock to the task object String() method. There seems to be a transient/inconsistent data race condition with this method which was found in our unit tests. For example, one case of this that has happened is in the following run while running TestTaskWithCircularDependency test case.

Error log encountered:

WARNING: DATA RACE
Read at 0x00c000a86e38 by goroutine 11:
  github.com/aws/amazon-ecs-agent/agent/api/task.(*Task).stringUnsafe()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/api/task/task.go:2920 +0x184
  github.com/aws/amazon-ecs-agent/agent/api/task.(*Task).String()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/api/task/task.go:2913 +0x26
  fmt.(*pp).handleMethods()
      /opt/hostedtoolcache/go/1.22.5/x64/src/fmt/print.go:673 +0x6ea
  fmt.(*pp).printArg()
      /opt/hostedtoolcache/go/1.22.5/x64/src/fmt/print.go:756 +0xb4b
  fmt.(*pp).doPrintf()
      /opt/hostedtoolcache/go/1.22.5/x64/src/fmt/print.go:1075 +0x592
  fmt.Sprintf()
      /opt/hostedtoolcache/go/1.22.5/x64/src/fmt/print.go:239 +0x5c
  github.com/cihub/seelog.(*logFormattedMessage).String()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/logger.go:369 +0x75
  github.com/cihub/seelog.(*commonLogger).processLogMsg()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/logger.go:312 +0xca
  github.com/cihub/seelog.(*asyncLogger).processQueueElement()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/behavior_asynclogger.go:115 +0x199
  github.com/cihub/seelog.(*asyncLoopLogger).processItem()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/behavior_asynclooplogger.go:57 +0x1f3
  github.com/cihub/seelog.(*asyncLoopLogger).processQueue()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/behavior_asynclooplogger.go:63 +0x36
  github.com/cihub/seelog.NewAsyncLoopLogger.gowrap1()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/behavior_asynclooplogger.go:40 +0x33

Previous write at 0x00c000a86e38 by goroutine 2015:
  github.com/aws/amazon-ecs-agent/agent/api/task.(*Task).SetDesiredStatus()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/api/task/task.go:2785 +0xa4
  github.com/aws/amazon-ecs-agent/agent/engine.(*DockerTaskEngine).AddTask()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/engine/docker_task_engine.go:1203 +0xf04
  github.com/aws/amazon-ecs-agent/agent/engine/dependencygraph.ValidDependencies()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/engine/dependencygraph/graph.go:101 +0x344
  github.com/aws/amazon-ecs-agent/agent/engine/dependencygraph.dependenciesCanBeResolved()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/engine/dependencygraph/graph.go:130 +0x1b2
  github.com/aws/amazon-ecs-agent/agent/engine/dependencygraph.ValidDependencies()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/engine/dependencygraph/graph.go:101 +0x344
  github.com/aws/amazon-ecs-agent/agent/engine.(*DockerTaskEngine).AddTask()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/engine/docker_task_engine.go:1196 +0xd09
  github.com/aws/amazon-ecs-agent/agent/engine.TestTaskWithCircularDependency.gowrap2()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/engine/docker_task_engine_test.go:1367 +0x50

Goroutine 11 (running) created at:
  github.com/cihub/seelog.NewAsyncLoopLogger()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/behavior_asynclooplogger.go:40 +0x11c
  github.com/cihub/seelog.createLoggerFromFullConfig()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/log.go:73 +0x4b4
  github.com/cihub/seelog.LoggerFromConfigAsBytes()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/cfg_config.go:58 +0xf6
  github.com/cihub/seelog.init.3()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/vendor/github.com/cihub/seelog/log.go:55 +0xe4

Goroutine 2015 (running) created at:
  github.com/aws/amazon-ecs-agent/agent/engine.TestTaskWithCircularDependency()
      /home/runner/work/amazon-ecs-agent/amazon-ecs-agent/src/github.com/aws/amazon-ecs-agent/agent/engine/docker_task_engine_test.go:1367 +0x344
  testing.tRunner()
      /opt/hostedtoolcache/go/1.22.5/x64/src/testing/testing.go:1689 +0x21e
  testing.(*T).Run.gowrap1()
      /opt/hostedtoolcache/go/1.22.5/x64/src/testing/testing.go:1742 +0x44

Implementation details

Testing

Ran the TestTaskWithCircularDependency 500 times and it no longer encountered the race condition issue.

Commit
Linux unit test run

New tests cover the changes: No

Description for the changelog

Bugfix: Add read lock to task object String method

Additional Information

Does this PR include breaking model changes? If so, Have you added transformation functions?

Does this PR include the addition of new environment variables in the README?

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.