Add TiDB Cloud SQL proxy account

[lilin90]

What is changed, added or deleted? (Required)

Adds a new doc about TiDB Cloud SQL proxy account

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

Tips for choosing the affected version(s):

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.

• [ ] master (the latest development version)
• [ ] v8.4 (TiDB 8.4 versions)
• [ ] v8.3 (TiDB 8.3 versions)
• [ ] v8.2 (TiDB 8.2 versions)
• [ ] v8.1 (TiDB 8.1 versions)
• [ ] v8.0 (TiDB 8.0 versions)
• [x] 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)
• [ ] v5.3 (TiDB 5.3 versions)
• [ ] v5.2 (TiDB 5.2 versions)

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

• This PR is translated from:
• Other reference link(s):

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]]

Skipping CI for Draft Pull Request. If you want CI signal for your change, please convert it to an actual PR. You can still manually trigger a test run with /test all

[lilin90]

@zhoubasten Please take a look at and reply to these comments:

• https://github.com/pingcap/docs/pull/18696#discussion_r1731064085
• https://github.com/pingcap/docs/pull/18696#discussion_r1747794577
• https://github.com/pingcap/docs/pull/18696#discussion_r1772420431

[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2024-12-05 06:04:05.572514333 +0000 UTC m=+1307633.192168851: :ballot_box_with_check: agreed by hfxsd.

[lilin90]

Note: The changes in https://github.com/pingcap/docs/pull/18696/commits/93e482cfd0d5413a7aee263e668761abec641f9b have been confirmed by @zhoubasten.

[lilin90]

/approve

[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lilin90

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• ~~OWNERS~~ [lilin90]

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #19588.