Adds support for Elasticsearch 7.10.0

[bowenlan-amzn]

Description of changes:

1. integTest change PR example
   since their javaRestTest create its own sourceSet and binding it to their test env, we choose to create a task (RestIntegTestTask), still name as integTest. In the back, same name cluster will be created, so don't need to worry about cluster creation. But we need to bundle our plugin into the cluster.

   • old RestIntegTestTask
   • example to write own RestIntegTestTask code link

2. No executor anymore in localmasterlistener PR

3. run task now need to explicitly set cluster

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

[codecov]

Codecov Report

Merging #300 (0fad7d0) into master (f7a3982) will increase coverage by 0.20%.
The diff coverage is 94.44%.

@@             Coverage Diff              @@
##             master     #300      +/-   ##
============================================
+ Coverage     80.17%   80.38%   +0.20%     
- Complexity      196      197       +1     
============================================
  Files           151      151              
  Lines          5165     5169       +4     
  Branches        673      674       +1     
============================================
+ Hits           4141     4155      +14     
+ Misses          666      656      -10     
  Partials        358      358              

Impacted Files	Coverage Δ	Complexity Δ
...forelasticsearch/alerting/model/destination/SNS.kt	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...arch/alerting/core/schedule/JobSchedulerMetrics.kt	81.25% <0.00%> (ø)	6.00 <0.00> (ø)
...roforelasticsearch/alerting/alerts/AlertIndices.kt	65.64% <60.00%> (-0.50%)	0.00 <0.00> (ø)
...endistroforelasticsearch/alerting/MonitorRunner.kt	78.00% <100.00%> (ø)	0.00 <0.00> (ø)
...stroforelasticsearch/alerting/alerts/AlertError.kt	80.95% <100.00%> (ø)	0.00 <0.00> (ø)
...stroforelasticsearch/alerting/alerts/AlertMover.kt	72.72% <100.00%> (ø)	0.00 <0.00> (ø)
...sticsearch/alerting/model/ActionExecutionResult.kt	87.09% <100.00%> (ø)	0.00 <0.00> (ø)
...opendistroforelasticsearch/alerting/model/Alert.kt	89.47% <100.00%> (+1.97%)	0.00 <0.00> (ø)
...endistroforelasticsearch/alerting/model/Monitor.kt	89.51% <100.00%> (+0.80%)	0.00 <0.00> (ø)
...endistroforelasticsearch/alerting/model/Trigger.kt	84.21% <100.00%> (ø)	0.00 <0.00> (ø)
... and 29 more

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[dbbaughe]

Can you confirm the previous functionality still works.
i.e. can you still do all of these things:
Debug the source code with breakpoints
Debug the integration tests running against the integTest cluster
Run multi node tests (Did alerting have this? I don't see a multi node check on this PR)