Require `last_engine_commit.sh` after 3.33 release is archived

[matanlurey]

To work around #168673, we'll do a conditional test for bin/internal/last_engine_commit.sh, using a hardcoded git command if the file is missing. Once every release that is missing last_engine_commit.sh is archived (no more hotfix releases), we can remove this tech debt.

[matanlurey]

Fixed at HEAD.

[github-actions]

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