Add unit tests for sql plugin registration

[Shaddoll]

What changed?
Add unit tests for sql plugin registration

Why?
Improve test coverage

How did you test it?
unit test

Potential risks

Release notes

Documentation Changes

[coveralls]

Pull Request Test Coverage Report for Build 018e0a8b-1a9b-4eda-815d-5a18215d7aea

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 113 unchanged lines in 17 files lost coverage.
• Overall coverage decreased (-0.009%) to 62.917%

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Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	1	88.06%
common/peerprovider/ringpopprovider/config.go	2	81.58%
common/persistence/historyManager.go	2	66.67%
service/frontend/api/handler.go	2	62.05%
service/history/execution/mutable_state_util.go	2	37.63%
common/persistence/nosql/nosqlplugin/cassandra/workflow.go	3	61.93%
common/persistence/statsComputer.go	3	94.64%
common/archiver/filestore/historyArchiver.go	4	80.95%
common/persistence/nosql/nosqlplugin/cassandra/tasks.go	4	76.09%
service/history/task/transfer_standby_task_executor.go	4	87.01%

Totals
Change from base Build 018e093f-1deb-4964-90de-0337cc45040c:	-0.009%
Covered Lines:	92999
Relevant Lines:	147813

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💛 - Coveralls