docs: roll back v8.5.6 Top SQL note and refresh v8.5 screenshots

[yibin87]

What is changed, added or deleted? (Required)

• Roll back the v8.5.6 release note entry about Top SQL collecting TiKV Network IO / Logical IO metrics.
• Refresh the v8.5 Top SQL screenshots under media/dashboard/.

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)

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

Translated from: pingcap/docs-cn#21657

• Other reference link(s):
  • releases/release-8.5.6.md
  • media/dashboard/v8.5-top-sql-*.png

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

[gemini-code-assist]

Code Review

This pull request removes documentation entries related to the collection of TiKV network traffic and logical I/O metrics for Top SQL from the v8.5.6 release notes. Specifically, it deletes the feature description, the associated TiKV configuration parameter (resource-metering.enable-network-io-collection), and the corresponding improvement bullet point. I have no feedback to provide as there were no review comments to evaluate.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-05-21 09:17:39.829146013 +0000 UTC m=+28590.470002816: ☑️ agreed by qiancai.

[qiancai]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: qiancai

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