Add unit tests for the util functions in data_manager_interface

[timl3136]

What changed?
Add unit tests for the remaining uncovered unit tests in data_manager_interface file

Why?
Improve test coverage and stability

How did you test it?
Unit tests

Potential risks
Nothing since it's only unit tests

Release notes

Documentation Changes

[codecov]

Codecov Report

Merging #5742 (ef1239d) into master (83f9aca) will increase coverage by 0.00%.
The diff coverage is n/a.

❗ Current head ef1239d differs from pull request most recent head 30cecf9. Consider uploading reports for the commit 30cecf9 to get more accurate results

Additional details and impacted files

see 7 files with indirect coverage changes

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[coveralls]

Pull Request Test Coverage Report for Build 018e16ef-1ba4-443c-a82d-916cd06e3961

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 46 unchanged lines in 12 files lost coverage.
• Overall coverage increased (+0.06%) to 63.91%

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Files with Coverage Reduction	New Missed Lines	%
common/persistence/sql/sqlplugin/postgres/db.go	2	80.0%
common/persistence/sql/sqlplugin/postgres/task.go	2	73.4%
common/task/fifo_task_scheduler.go	2	87.63%
common/task/weighted_round_robin_task_scheduler.go	2	89.05%
common/util.go	2	91.69%
service/history/task/fetcher.go	2	85.57%
service/matching/db.go	2	73.23%
service/matching/taskListManager.go	2	80.46%
common/log/tag/tags.go	3	50.18%
service/matching/taskReader.go	5	83.55%

Totals
Change from base Build 018e16ec-6c91-4f51-bb5b-51b534dddc09:	0.06%
Covered Lines:	93692
Relevant Lines:	146599

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💛 - Coveralls