br: merge range in lightweight when snapshot restore (#50648)

[ti-chi-bot]

This is an automated cherry-pick of #50648

What problem does this PR solve?

Issue Number: close #50613

Problem Summary:
Merge file ranges takes too much time when the file ranges's size is much large.

What changed and how does it work?

use the O(n) algorithm

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

[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Leavrth, YuJuncen

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• OWNERS [Leavrth,YuJuncen]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-03-27 10:25:18.264443355 +0000 UTC m=+2063545.286689736: ☑️ agreed by YuJuncen.
• 2024-03-28 02:40:39.896219621 +0000 UTC m=+2122066.918466007: ☑️ agreed by Leavrth.

[Leavrth]

/retest