ddl: increasing value of partition by range columns fix (#32748)

[mjonss]

What problem does this PR solve?

Issue Number: close #32748

Problem Summary:
Unnecessary check for equal values compared folded values, which is wrong for _bin collations.

What is changed and how it works?

Removed the check, since the following check is now collation aware.

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

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• djshow832
• xiongjiwei

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[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/44d48eaaa7f6080c578843aa9a927d2a947e47bb

[xiongjiwei]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 1eeb0a8

[ti-chi-bot]

@mjonss: Your PR was out of date, I have automatically updated it for you.

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