br: restore json type

[3pointer]

First-time contributors' checklist

• I've signed Contributor License Agreement that's required for repo owners to accept my contribution.

What is changed, added or deleted? (Required)

Which TiDB version(s) do your changes apply to? (Required)

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By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions (in Chinese).

• master (the latest development version)
• v6.6 (TiDB 6.6 versions)
• v6.5 (TiDB 6.5 versions)
• v6.4 (TiDB 6.4 versions)
• v6.1 (TiDB 6.1 versions)
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• Delete files
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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• shichun-0415

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After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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[shichun-0415]

LGTM

[shichun-0415]

/remove status LGT1
/status LGT2
/merge

[ti-chi-bot]

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

Commit hash: eea53f0

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.4: #13414.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #13415.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.6: #13416.