fix wrong legend name

[bufferflies]

What problem does this PR solve?

Issue Number: Close #7081

What is changed and how does it work?

Check List

Tests

• Manual test (add detailed scripts or steps below)

Code changes

Side effects

Related changes

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• lhy1024

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[bufferflies]

/merge

[ti-chi-bot]

@bufferflies: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 7ce8493

[lhy1024]

Do we need to pick it to other branches?

[bufferflies]

Do we need to pick it to other branches?

no need, it's updated in #6969