Delete unused scripts/upload.py (#21482)

[ti-chi-bot]

This is an automated cherry-pick of #21482

What is changed, added or deleted? (Required)

Deleted scripts/upload.py. After the migration to Tencent Cloud, this upload script is no longer used.

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)
• v5.4 (TiDB 5.4 versions)

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

• This PR is translated from: Delete unused scripts/upload.py docs#22653
• Other reference link(s): scripts/upload.py (deleted)

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]

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