Added unit tests for service/history/handler

[timl3136]

What changed?
Added more unit tests for methods in history/hander.go

Why?
Increase test coverage and stability

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 64.10%. Comparing base (2ac145f) to head (03fe5ef).

Additional details and impacted files

see 7 files with indirect coverage changes

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[coveralls]

Pull Request Test Coverage Report for Build 018f547c-082a-459c-9a5d-7c1b345bc34b

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 48 unchanged lines in 8 files lost coverage.
• Overall coverage increased (+0.09%) to 68.211%

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Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	1	89.05%
service/history/queue/timer_queue_processor_base.go	1	77.66%
common/task/parallel_task_processor.go	2	93.06%
service/matching/taskListManager.go	2	80.65%
service/history/task/fetcher.go	3	86.6%
common/task/fifo_task_scheduler.go	4	85.57%
service/history/execution/mutable_state_task_refresher.go	15	62.03%
service/history/task/task_util.go	20	70.57%

Totals
Change from base Build 018f5467-b337-442d-bcf0-8ad761c213c7:	0.09%
Covered Lines:	100196
Relevant Lines:	146892

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💛 - Coveralls