pkg/backup: fix test case br_autoid for the previous cherry-pick

[tiancaiamao]

What problem does this PR solve?

Issue Number: ref #46093

Problem Summary:

What is changed and how it works?

In the previous cherry-pick #46217
I didn't notice the subtle difference between master and v6.5 branch.

Before this PR:
91f6752#diff-e611f02c279107dbfa433418c809e99569c0b24c2ea92cc7aef9f7f41fbcc3b9L581

old version use

idAlloc.NextGlobalAutoID()

and master use

rowID + 1

The semantic is the same, but the tiny code struct change make the previous cherry-pick introduce a bug and break CI.

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

[tiprow]

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3pointer, Defined2014

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-08-21 02:39:26.017461579 +0000 UTC m=+1117130.566477550: ☑️ agreed by Defined2014.
• 2023-08-21 02:41:44.745811552 +0000 UTC m=+1117269.294827538: ☑️ agreed by 3pointer.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-6.5@7de3979). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

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