Expand JOB_TYPE documentation for ADMIN SHOW DDL... output (#14461)

[ti-chi-bot]

This is an automated cherry-pick of #14461

What is changed, added or deleted? (Required)

• Expand JOB_TYPE documentation for ADMIN SHOW DDL... output.
• Add note about temp-dir to tidb_enabe_fast_reorg docs.

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• 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: Expand JOB_TYPE documentation for ADMIN SHOW DDL... output docs#13395
• 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

[qiancai]

/approve

[ti-chi-bot]

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