parser: reset lexer.identifierDot correctly when reusing parsers (#45903)

[ti-chi-bot]

This is an automated cherry-pick of #45903

What problem does this PR solve?

Issue Number: close #45898

Problem Summary: parser: reset lexer.identifierDot correctly when reusing parsers

What is changed and how it works?

parser: reset lexer.identifierDot correctly when reusing parsers

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, tiancaiamao

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-08-08 09:21:44.338891483 +0000 UTC m=+18068.887907470: ☑️ agreed by hawkingrei.
• 2023-08-08 09:26:30.327578883 +0000 UTC m=+18354.876594869: ☑️ agreed by tiancaiamao.

[qw4990]

/test unit-test

[tiprow]

@qw4990: No presubmit jobs available for pingcap/tidb@release-6.1

In response to this:

/test unit-test

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[hawkingrei]

/retest