create-index: remove the description that no stats are collected for mv index

[Oreoxmt]

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).

• [x] master (the latest development version)
• [x] v8.0 (TiDB 8.0 versions)
• [ ] v7.6 (TiDB 7.6 versions)
• [ ] v7.5 (TiDB 7.5 versions)
• [ ] v7.4 (TiDB 7.4 versions)
• [ ] v7.3 (TiDB 7.3 versions)
• [ ] v7.1 (TiDB 7.1 versions)
• [ ] v6.5 (TiDB 6.5 versions)
• [ ] v6.1 (TiDB 6.1 versions)
• [ ] v5.4 (TiDB 5.4 versions)
• [ ] v5.3 (TiDB 5.3 versions)
• [ ] v5.2 (TiDB 5.2 versions)
• [ ] v5.1 (TiDB 5.1 versions)
• [ ] v5.0 (TiDB 5.0 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s): https://github.com/pingcap/tidb/issues/46539

Do your changes match any of the following descriptions?

• [ ] Delete files
• [ ] Change aliases
• [ ] Need modification after applied to another branch
• [ ] Might cause conflicts after applied to another branch

[ti-chi-bot[bot]]

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[Oreoxmt]

/cc @hfxsd

[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-02-29 10:38:22.179516253 +0000 UTC m=+1131190.927139364: :ballot_box_with_check: agreed by hfxsd.

[Oreoxmt]

/approve

[ti-chi-bot[bot]]

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