Stop the ratelimiter collections when stopping the service

[Groxx]

Rather obviously missed in retrospect, oops.

These can be stopped basically anywhere without causing issues, but after the handlers are stopped there should be no more in-bound requests worth counting (the "stopping" check will stop anything from actually "running").
So around here seems like the most-reasonable place to stop sharing load info with others.

[coveralls]

Pull Request Test Coverage Report for Build 01907562-f5f0-40b6-8908-451d758b6138

Details

• 9 of 17 (52.94%) changed or added relevant lines in 1 file are covered.
• 22 unchanged lines in 7 files lost coverage.
• Overall coverage increased (+0.003%) to 71.512%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
service/frontend/service.go	9	17	52.94%

Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	1	89.05%
tools/cli/admin_db_decode_thrift.go	2	70.51%
service/matching/tasklist/matcher.go	2	90.91%
common/persistence/historyManager.go	2	66.67%
service/history/task/transfer_standby_task_executor.go	3	86.64%
common/persistence/statsComputer.go	3	98.18%
service/history/shard/context.go	9	78.13%

Totals
Change from base Build 019074f6-fb21-4003-bd1e-30edc2b1e424:	0.003%
Covered Lines:	105315
Relevant Lines:	147269

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💛 - Coveralls