*: add support for tiflash_mpp label/tiflash ReadNode

[guo-shaoge]

Signed-off-by: guo-shaoge shaoge1994@163.com

What problem does this PR solve?

Issue Number: Close #4836

What is changed and how does it work?

*: add support for tiflash_mpp label/tiflash ReadNode

Make PD be compatible with new tiflash_mpp label(<engine, tiflash_mpp>).

Check List

Tests

N/A

Code changes

N/A

Side effects

N/A

Related changes

N/A

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[guo-shaoge]

/run-all-tests

[guo-shaoge]

/run-all-tests

[guo-shaoge]

/run-all-tests

[nolouch]

Could you add some tests?

[guo-shaoge]

Could you add some tests?

Sorry for the late reply. The following cases are added:

1. testHotWriteRegionSchedulerSuite.TestWithTiFlashMPP: test hot_region_scheduler with tiflash_mpp nodes.
2. testClusterInfoSuite.TestEngineLabel: test if engine label is correct when PutStore
3. testClusterInfoSuite.TestRegionLabelIsolationLevel: isolation level of tiflash/tiflash_mpp will be ignored(see updateRegionsLabelLevelStats())

I'm writing more complicated cases using test-infra.

[ti-chi-bot]

@guo-shaoge: PR needs rebase.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.