Removed useless metrics tag from the workflowIDcache

[jakobht]

What changed?
Removed useless metrics tag for the workflowIDcache

Why?
There is no need to tag the cachesize with a domain as the cache is
host-global, and shared between the domains.

How did you test it?

Potential risks

Release notes

Documentation Changes

[coveralls]

Pull Request Test Coverage Report for Build 018d8cc2-c921-428f-ba05-967c414688cb

• 0 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 94 unchanged lines in 13 files lost coverage.
• Overall coverage increased (+0.002%) to 62.69%

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Files with Coverage Reduction	New Missed Lines	%
common/peerprovider/ringpopprovider/config.go	2	81.58%
common/persistence/executionManager.go	2	78.94%
common/persistence/statsComputer.go	2	95.71%
service/history/task/transfer_standby_task_executor.go	2	86.6%
service/matching/taskListManager.go	2	80.2%
common/persistence/dataManagerInterfaces.go	3	60.91%
service/history/queue/timer_gate.go	4	95.83%
service/history/task/fetcher.go	4	85.05%
service/history/shard/context.go	9	66.7%
service/history/execution/context.go	14	68.37%

Totals
Change from base Build 018d8817-7fc3-47a1-90d8-455b224e898e:	0.002%
Covered Lines:	92234
Relevant Lines:	147128

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💛 - Coveralls