hot fix for unit test cases that might cause a failure

[bowenxia]

What changed?
Change the error assertion from "equal to err.Error()" to "equal to error"

Why?
hot fix for unit test cases that might cause a failure

How did you test it?

Potential risks

Release notes

Documentation Changes

[codecov]

Codecov Report

Merging #5787 (5318469) into master (3c7c303) will decrease coverage by 0.02%.
The diff coverage is n/a.

❗ Current head 5318469 differs from pull request most recent head 011b67e. Consider uploading reports for the commit 011b67e to get more accurate results

Additional details and impacted files

see 8 files with indirect coverage changes

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[coveralls]

Pull Request Test Coverage Report for Build 018e3e0b-2d0f-4c90-a1a8-f2e712f1bb37

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 73 unchanged lines in 18 files lost coverage.
• Overall coverage increased (+0.008%) to 64.858%

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Files with Coverage Reduction	New Missed Lines	%
tools/cli/admin_db_decode_thrift.go	1	71.79%
common/task/weighted_round_robin_task_scheduler.go	2	89.05%
common/task/parallel_task_processor.go	2	93.06%
common/peerprovider/ringpopprovider/config.go	2	81.58%
service/matching/db.go	2	73.23%
service/history/execution/mutable_state_builder.go	2	70.3%
service/history/task/fetcher.go	2	85.05%
common/persistence/historyManager.go	2	66.67%
common/log/tag/tags.go	3	50.18%
service/history/queue/timer_gate.go	3	95.83%

Totals
Change from base Build 018e38e2-422c-460d-92ea-2946554c16c2:	0.008%
Covered Lines:	94537
Relevant Lines:	145760

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💛 - Coveralls