bump TiDB Operator to v1.5.5, TiDB to v7.5.5

[csuzhangxc]

What problem does this PR solve?

What is changed and how does it work?

Code changes

• Has Go code change
• Has CI related scripts change

Tests

• Unit test
• E2E test
• Manual test
• No code

Side effects

• Breaking backward compatibility
• Other side effects:

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release Notes

Please refer to Release Notes Language Style Guide before writing the release note.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[csuzhangxc]

/run-all-tests

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.89%. Comparing base (d032996) to head (3bfe1d3).
Report is 34 commits behind head on release-1.5.

❗ Current head 3bfe1d3 differs from pull request most recent head ca49191

Please upload reports for the commit ca49191 to get more accurate results.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-1.5    #6040      +/-   ##
===============================================
- Coverage        61.53%   60.89%   -0.65%     
===============================================
  Files              229      229              
  Lines            29331    29920     +589     
===============================================
+ Hits             18050    18220     +170     
- Misses            9499     9880     +381     
- Partials          1782     1820      +38     

Flag	Coverage Δ
unittest	60.89% <ø> (-0.65%)	⬇️

[csuzhangxc]

/run-pull-e2e-kind-across-kubernetes

[csuzhangxc]

/run-pull-e2e-kind

[csuzhangxc]

/run-pull-e2e-kind-serial