Code cleanup for sql package

[Shaddoll]

What changed?

• Rename files to snake case
• Delete unused functions

Why?
Code cleanup

How did you test it?
unit tests

Potential risks

Release notes

Documentation Changes

[codecov]

Codecov Report

Merging #5756 (fc78230) into master (09c3743) will decrease coverage by 0.25%.
The diff coverage is n/a.

❗ Current head fc78230 differs from pull request most recent head 86604f6. Consider uploading reports for the commit 86604f6 to get more accurate results

Additional details and impacted files

see 23 files with indirect coverage changes

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[coveralls]

Pull Request Test Coverage Report for Build 018e1f17-e081-4bf7-9b51-a56eed7293dd

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 104 unchanged lines in 12 files lost coverage.
• Overall coverage increased (+0.09%) to 63.755%

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Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	2	88.56%
common/persistence/sql/sqlplugin/postgres/task.go	2	73.4%
common/persistence/sql/sqlplugin/postgres/db.go	2	80.0%
service/matching/taskListManager.go	2	79.7%
common/persistence/nosql/nosqlplugin/cassandra/workflow.go	3	71.41%
common/persistence/statsComputer.go	3	93.57%
service/frontend/wrappers/metered/metered.go	4	65.5%
common/task/fifo_task_scheduler.go	5	80.41%
service/history/task/transfer_standby_task_executor.go	6	86.6%
common/persistence/nosql/nosqlplugin/cassandra/workflow_parsing_utils.go	19	79.13%

Totals
Change from base Build 018e1eef-eebc-4bcc-8209-ef12d28b308e:	0.09%
Covered Lines:	92939
Relevant Lines:	145775

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💛 - Coveralls