tso: replace priorityCheck ResetLeader with TransferPrimary

[HuSharp]

What problem does this PR solve?

The issue detail process is #8533 (comment)

tso's priority uses ResetLeader instead of moveLeader.
The process is:

• secondary: primary check priority -> resetLeader -> secondary exit watch -> secondary enter campaign -> secondary select new leader
• primary: primary check priority -> resetLeader -> (need 200ms tick)[time gap] primary finds out there is not primary -> exit campaign -> primary enter campaign

Secondary can be elected as new primary because of time gap which is not stable!!!

For example, if the secondary io jitters and doesn't elected as new primary, the old primary will be elected, and then it will loop through the priority check logic again.

Issue Number: Close #8533

What is changed and how does it work?

• Because transfer primary is actually as move etcd leader.
• So replace ResetLeader with transfer primary, which is more time efficient and can avoid time lag.

Check List

Tests

• Integration test
• Manual test (add detailed scripts or steps below)

Release note

tso: replace priorityCheck ResetLeader with TransferPrimary

[codecov]

Codecov Report

Attention: Patch coverage is 55.00000% with 9 lines in your changes missing coverage. Please review.

Project coverage is 77.56%. Comparing base (98e0407) to head (fd70e06).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8597      +/-   ##
==========================================
- Coverage   77.60%   77.56%   -0.04%     
==========================================
  Files         474      474              
  Lines       61864    61879      +15     
==========================================
- Hits        48007    47994      -13     
- Misses      10317    10343      +26     
- Partials     3540     3542       +2     

Flag	Coverage Δ
unittests	77.56% <55.00%> (-0.04%)	⬇️

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lhy1024, rleungx

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-06 05:44:32.980891241 +0000 UTC m=+595997.498944161: ☑️ agreed by lhy1024.
• 2024-09-09 06:52:10.054474092 +0000 UTC m=+252799.794898023: ☑️ agreed by rleungx.