docs: restore v8.5 TopSQL multidimensional docs for v8.5.7

[yibin87]

What is changed, added or deleted? (Required)

• Restore the Top SQL multidimensional and TiKV network IO collection docs on release-8.5, because the feature support is back in v8.5.7 after being rolled back from v8.5.6.
• Update the related version marks from v8.5.6 to v8.5.7 in dashboard/top-sql.md, tikv-configuration-file.md, and system-variables.md.
• Remove the leftover InPacketBytes and OutPacketBytes items from releases/release-8.5.6.md so the v8.5.6 release note stays aligned with the earlier rollback.

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

• master (the latest development version)
• v9.0 (TiDB 9.0 versions)
• v8.5 (TiDB 8.5 versions)
• v8.1 (TiDB 8.1 versions)
• v7.5 (TiDB 7.5 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)

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

• Other reference link(s):
  • docs: roll back v8.5.6 TopSQL multidimensional docs #21652
  • docs: roll back v8.5.6 Top SQL note and refresh v8.5 screenshots #21657
  • docs: correct Top SQL multi-dimensional metrics support to v8.5.7 #21716
  • dashboard/top-sql.md
  • tikv-configuration-file.md
  • system-variables.md
  • releases/release-8.5.6.md

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]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign ran-huang for approval. For more information see the Code Review Process.
Please ensure that each of them provides their approval before proceeding.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment