privilege: fix grant and revoke for global level grant(#29675)

[yiwen92]

What problem does this PR solve?

Issue Number: close #29675

Problem Summary:
Fix grant and revoke for global level grant in information schema.

What is changed and how it works?

When sql contain global level grant like ., do not fill dbName, this can skip privilege check in later and execute successfully without error.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

This is a fix for grant global level case in v4.0 and v5.0

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• morgo
• tiancaiamao

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[yiwen92]

/cc @morgo

[yiwen92]

/assignee @yiwen92

[yiwen92]

/cc @bb7133 PTAL,thx

[tiancaiamao]

PTAL @morgo

[VelocityLight]

/merge

[ti-chi-bot]

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

Commit hash: 00b768a

[ti-chi-bot]

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