refine LAC computation of avg_speed

[guo-shaoge]

What problem does this PR solve?

Issue Number: close #8287

Problem Summary:

1. refine calculation of avg_speed:
   1. before: avg_speed may be negative because of worker consume too many RU, like:
      1. 
   2. after: calculate avg_speed every 5 seconds. And ru_consumption_speed is the avg speed of last 5 seconds. ru_consumption_delta is the ru consumption of last 5 seconds, it will be set to zero after report consumption to GAC every 5 seconds.
      1. 

Others:

1. Add needNotifyStopTrickleMode to exit trickle mode timely. Otherwise it's possiable LAC cannot talk to GAC because always got enough token(a.k.a. the fill rate of trickle mode is large enough)
2. Change ACQUIRE_RU_AMPLIFICATION from 1.1 to 1.5. Although tidb also use 1.1, but IMO it's a little small.

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

[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:

• 2023-11-02 02:27:40.9177843 +0000 UTC m=+3092858.504894430: ☑️ agreed by windtalker.
• 2023-11-02 04:05:38.426004357 +0000 UTC m=+3098736.013114488: ☑️ agreed by SeaRise.

[ti-chi-bot]

@guo-shaoge: Your PR was out of date, I have automatically updated it for you.

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/run-all-tests

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[guo-shaoge]

/run-integration-test

[guo-shaoge]

/hold

[guo-shaoge]

/run-all-tests

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #8300.