make tiflash scale-in faster

[guo-shaoge]

What problem does this PR solve?

Issue Number: close #8433

Problem Summary:

1. change ConfigReloader, this is to make it stop as soon as possible.
2. For MetricsPrometheus, cancel without waiting

after the above change, the scale-in time changed from 9sec to 2.91sec
(check slow_stop.log.md VS stop_fast.md for deail)

Other:

1. move lac and pipeline and FlashGrpcServerHolder position. Make them to destruct first.
2. For AutoScaler, it use the following step
   1. send SIGTERM to let lac.stop() is called, so lac will do cleanup
   2. check if 3930 port is down. When it's down, AutoScaler can make sure lac.stop() is called
   3. AutoScaler send SIGKILL to tiflash.

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[guo-shaoge]

/run-all-tests

[guo-shaoge]

/run-all-tests

[SeaRise]

lgtm

[windtalker]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: SeaRise, windtalker

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-11-30 05:50:37.950357052 +0000 UTC m=+1074666.615583244: ☑️ agreed by SeaRise.
• 2023-11-30 05:57:42.538453832 +0000 UTC m=+1075091.203680027: ☑️ agreed by windtalker.

[ti-chi-bot]

@guo-shaoge: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

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