Feat: support customizing the readiness probe for tidb

[fgksgf]

What problem does this PR solve?

In some case, tidb servers may not be ready to serve traffic even the readiness probe can establish connection on port 4000 or 10080. Therefore, a better way maybe using the mysql protocol to probe.

What is changed and how does it work?

This PR adds a CustomizedReadinessProbe field, we can provide our own binary as the readiness probe.

Code changes

• [x] Has Go code change
• [ ] Has CI related scripts change

Tests

• [x] Unit test
• [x] E2E test
• [x] 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.

Support customizing the readiness probe for tidb

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 67.47%. Comparing base (645d9e9) to head (1f96a81).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5580 +/- ## ========================================== + Coverage 61.51% 67.47% +5.96% ========================================== Files 235 246 +11 Lines 30258 34185 +3927 ========================================== + Hits 18612 23067 +4455 + Misses 9779 9185 -594 - Partials 1867 1933 +66 ``` | [Flag](https://app.codecov.io/gh/pingcap/tidb-operator/pull/5580/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | Coverage Δ | | |---|---|---| | [e2e](https://app.codecov.io/gh/pingcap/tidb-operator/pull/5580/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `46.58% <95.12%> (?)` | | | [unittest](https://app.codecov.io/gh/pingcap/tidb-operator/pull/5580/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | `61.55% <100.00%> (+0.04%)` | :arrow_up: |

[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: csuzhangxc

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/pingcap/tidb-operator/blob/master/OWNERS)~~ [csuzhangxc] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-03-20 07:06:01.086428375 +0000 UTC m=+1446788.108674748: :ballot_box_with_check: agreed by csuzhangxc.

[csuzhangxc]

/run-all-tests

[csuzhangxc]

/run-pull-e2e-kind-serial

[csuzhangxc]

/run-pull-e2e-kind-tikv-scale-simultaneously

[fgksgf]

/run-pull-e2e-kind-serial

[fgksgf]

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