fix(ssh): validate job dir cleanup against configured remote_base_dir

[mmaxjr]

Fixes #69813

Problem

SSHRemoteJobOperator lets users set a custom remote_base_dir, and it's
correctly validated for safety (_validate_base_dir) and used to build
job_dir via RemoteJobPaths. Execution and monitoring both work fine
with it.

But _cleanup_remote_job calls build_posix_cleanup_command/
build_windows_cleanup_command, which always validated job_dir against
the hardcoded default base directory (_validate_job_dir), not the one
actually configured. So cleanup for any job using a custom
remote_base_dir always raised:

[boring-cyborg]

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[potiuk]

Thanks — this is a close call, and sorry to close it. Three PRs independently fixed this bug; I am going with #69885, open since 14 July.

Yours is good work and better in two respects: the docstring actually explains why a caller with a custom base dir must pass it, and you linked the originating issue #69813. #69885 has the edge on coverage though — it pins the rejection case on Windows as well as POSIX, whereas this covers the negative path for POSIX only. On a validation guard the refusals are the part most worth locking down.

Also worth knowing: #70091 has since rewritten these same command builders on main to use shlex.quote, so all three branches conflicted. I resolved that on #69885 rather than sending it back.

I would rather not lose your docstring — if you would like to carry it and the issue link over as a follow-up once #69885 lands, that would genuinely improve the result.

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Drafted-by: Claude Code (Opus 5); reviewed by @potiuk before posting