txn: restore failed due to file end key is empty (#52572)

[ti-chi-bot]

This is an automated cherry-pick of #52572

What problem does this PR solve?

Issue Number: close #52574

Problem Summary:
Restore txn kv might failed about handling empty end key. This PR fixed it.

What changed and how does it work?

Don't encode empty value of end key.

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.

Fix the issue that restore txn kv may report invalid range error.

[3pointer]

/test pull_br_integration_test

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[3pointer]

/test pull-br-integration-test

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[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 8 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-8.1@42b624c). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.1     #54998   +/-   ##
================================================
  Coverage               ?   71.3071%           
================================================
  Files                  ?       1465           
  Lines                  ?     422534           
  Branches               ?          0           
================================================
  Hits                   ?     301297           
  Misses                 ?     100797           
  Partials               ?      20440           

Flag	Coverage Δ
unit	71.3071% <71.4285%> (?)

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

Components	Coverage Δ
dumpling	53.9957% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	41.0740% <0.0000%> (?)

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3pointer, Leavrth

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-29 09:07:48.394841301 +0000 UTC m=+173984.674889370: ☑️ agreed by 3pointer.
• 2024-07-29 09:21:02.017039583 +0000 UTC m=+174778.297087652: ☑️ agreed by Leavrth.