parser: truncate keywords.go when re-creating it (#49634)

[ti-chi-bot]

This is an automated cherry-pick of #49634

What problem does this PR solve?

Issue Number: ref #48801

Problem Summary:

The code added in #48807 doesn't truncate the file when re-creating it. This might lead to left over bits of previous versions if the new file is shorter.

What changed and how does it work?

Check List

Tests

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

  • I checked and no code files have been changed.

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-7.5@4a6f3e5). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.5     #54221   +/-   ##
================================================
  Coverage               ?   72.0278%           
================================================
  Files                  ?       1411           
  Lines                  ?     410759           
  Branches               ?          0           
================================================
  Hits                   ?     295861           
  Misses                 ?      95010           
  Partials               ?      19888           

Flag	Coverage Δ
unit	72.0278% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9913% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.4477% <0.0000%> (?)

[bb7133]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bb7133, dveeden

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-06-26 06:20:13.600775153 +0000 UTC m=+786940.086263983: ☑️ agreed by dveeden.
• 2024-06-28 15:56:38.346165174 +0000 UTC m=+994324.831654004: ☑️ agreed by bb7133.