Refactor config methods for internal use

[yycptt]

What changed?

• Export config validate() and fillDefaults() methods for internal use since internal server is not using the Config struct
• Move logic that will change persistence config values to pesistenceConfig.FillDefaults()

Why?

• For internal server release

How did you test it?

• Tested in internal testing cluster

Potential risks

• N/A, logic is the same

Release notes

Documentation Changes

[coveralls]

Pull Request Test Coverage Report for Build ae5ea1d7-80a9-4964-935c-b733b62d6859

• 28 of 29 (96.55%) changed or added relevant lines in 3 files are covered.
• 73 unchanged lines in 10 files lost coverage.
• Overall coverage increased (+0.02%) to 56.432%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
common/config/persistence.go	23	24	95.83%

Files with Coverage Reduction	New Missed Lines	%
common/config/persistence.go	1	84.91%
common/task/weightedRoundRobinTaskScheduler.go	1	89.64%
service/history/queue/timer_queue_processor_base.go	1	78.56%
service/history/execution/mutable_state_builder.go	2	69.9%
service/history/queue/timer_queue_processor.go	2	58.77%
common/persistence/serialization/parser.go	4	65.41%
common/persistence/serialization/thrift_decoder.go	4	59.6%
common/task/fifoTaskScheduler.go	5	84.54%
common/persistence/sql/workflowStateMaps.go	17	84.2%
common/persistence/serialization/getters.go	36	58.53%

Totals
Change from base Build 0fd3f657-6315-48df-9bce-1450181f788c:	0.02%
Covered Lines:	79525
Relevant Lines:	140923

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💛 - Coveralls