*: fix broken links (#17041)

[ti-chi-bot]

This is an automated cherry-pick of #17041

What is changed, added or deleted? (Required)

Fix broken links:

• The link to the node-mysql2 documentation has been updated. The previous URL https://github.com/sidorares/node-mysql2/tree/master/documentation/en was removed in chore: remove duplicate documentation and examples sidorares/node-mysql2#2326. It now points to the current documentation site: https://sidorares.github.io/node-mysql2/docs/documentation.
• The link https://docs.pingcap.com/tidb/stable/dev-guide-sample-application-java is leading to a 404 error because develop/dev-guide-sample-application-java.md was removed without any redirect aliases being added.
• The TiDB Lightning package https://github.com/pingcap/tidb/tree/master/br/pkg/lightning was modified to https://github.com/pingcap/tidb/tree/master/lightning in lightning: move lightning directory out of br tidb#52247.

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)

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

• This PR is translated from: *: fix broken links docs-cn#17030
• 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]

/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

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