Add unit tests for replication fetchers

[Shaddoll]

What changed?
Add unit tests for replication fetchers

Why?
Improve coverage

How did you test it?
unit tests

Potential risks

Release notes

Documentation Changes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.85%. Comparing base (b76a4d8) to head (f7acff5).
Report is 2 commits behind head on master.

Additional details and impacted files

see 12 files with indirect coverage changes

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[coveralls]

Pull Request Test Coverage Report for Build 018f6538-b185-413c-93c4-4d35024143bd

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 225 unchanged lines in 13 files lost coverage.
• Overall coverage increased (+0.02%) to 69.171%

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Files with Coverage Reduction	New Missed Lines	%
common/task/parallel_task_processor.go	2	93.06%
tools/cli/admin_db_decode_thrift.go	2	70.51%
common/membership/hashring.go	2	84.69%
common/asyncworkflow/queue/consumer/default_consumer.go	3	92.13%
common/persistence/statsComputer.go	3	96.07%
service/history/task/transfer_standby_task_executor.go	4	86.21%
common/task/fifo_task_scheduler.go	4	83.51%
service/history/replication/task_executor.go	4	98.05%
service/history/task/fetcher.go	4	86.08%
service/history/queue/timer_queue_failover_processor.go	7	0.0%

Totals
Change from base Build 018f64f4-c8b4-4dac-8ed7-996896dd65a4:	0.02%
Covered Lines:	101625
Relevant Lines:	146919

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💛 - Coveralls