revert: cleanup sqlgram

[Oreoxmt]

What is changed, added or deleted? (Required)

Revert #16049.

After removing media/sqlgram from the master branch, docs in other branches that use the image from media/sqlgram fails to render. For example https://docs.pingcap.com/tidb/stable/sql-statement-use:

https://docs-archive.pingcap.com/tidb/v2.1/sql-statement-begin:

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)
• v8.1 (TiDB 8.1 versions)
• v8.0 (TiDB 8.0 versions)
• v7.6 (TiDB 7.6 versions)
• v7.5 (TiDB 7.5 versions)
• v7.4 (TiDB 7.4 versions)
• v7.1 (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):

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

[Oreoxmt]

/cc @dveeden @qiancai

[dveeden]

I assume this is a temporary solution?

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-04-07 07:53:07.732654817 +0000 UTC m=+776049.260195361: ☑️ agreed by qiancai.
• 2024-04-07 08:19:12.104106704 +0000 UTC m=+777613.631647250: ☑️ agreed by dveeden.

[Oreoxmt]

@dveeden To optimize the storage and costs for our CDN while reusing images across multiple versions, we currently "merge" all images under media/ across all branches and upload them to https://download.pingcap.com/images/docs/. This means we keep only one copy each image instead of one per branch. With 25 versions of TiDB docs in total, this approach saves significant storage space and costs. In most cases, we want to reuse images across versions to ensure consistency. Therefore, we cannot delete any images unless they are unused across all branches.

[Oreoxmt]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Oreoxmt

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

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [Oreoxmt]

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