Fix template-field validation timing in ssh provider operators

[bramhanandlingala]

Fixes the ssh provider's two entries from the #70296 exemption-list burn-down: SSHOperator and SSHRemoteJobOperator applied logic to template fields inside __init__, before Jinja templating runs.

• SSHRemoteJobOperator: remote_base_dir was validated in __init__, against the raw un-rendered template string. Moved validation to execute().
• SSHOperator: when a pre-built ssh_hook was injected, __init__ pushed the un-rendered remote_host onto it. Moved this to execute().

Both __init__ methods now only do plain assignments; the field-dependent logic runs in execute(), after templating.

Tests added for both operators covering the fixed behavior.

Related to #70296

Gen-AI disclosure: I used a generative AI tool to help identify the root
cause, write tests, and draft the PR description. I reviewed, tested, and
verified all changes locally before submitting.

Was generative AI tooling used to co-author this PR?

• Yes — Claude

Generated-by: Claude following the guidelines

[shahar1]

Thanks for your contribution!

1. Please fix static checks.
2. Make sure to remove the operator from the txt file.

[bramhanandlingala]

@shahar1

Thanks for the review!

Fixed the static check and removed both ssh entries from the exemption file. Let me know if anything else is needed.

[shahar1]

@bramhanandlingala noted an issue just before merging, please address this. Thank you! (please note that I merged main to your branch, so you might need to pull it first)

[bramhanandlingala]

Thanks @shahar1! Fixed — switched to if self.remote_host: as suggested, and added tests covering both the init no-mutation case and the execute() templated-value case. Ready for re-review.

[shahar1]

Thanks @shahar1! Fixed — switched to if self.remote_host: as suggested, and added tests covering both the init no-mutation case and the execute() templated-value case. Ready for re-review.

Please note that static checks currently fail

[bramhanandlingala]

Thanks for flagging, @shahar1 ! Dug into it — the failure wasn't related to the SSH changes at all. It was a stale exemption entry: SnowparkContainerJobOperator had already been fixed and its exemption removed on main, but a stale copy of that entry survived in our branch's validate_operators_init_exemptions.txt through a few merge conflict resolutions. Removed it and pushed — all checks are passing now. Ready for re-review whenever you have a chance!

Concerns addressed