Add logic to fail Pathways jobs on user code errors.

[RoshaniN]

Fixes / Features

• Set "--restart-on-user-code-failure" to fail JobSet on user code errors, as default for Pathways jobs. Note that max_restarts is 0 by default (unless altered for suspend/resume use-cases.)
• Pool the many Pathways workload create checks and setting into one function called ensure_pathways_workload_prerequisites()

Testing / Documentation

Tested locally with changes

Here roshanin-pw-test3 is correct and roshanin-pw-test4 contains a typo in user code.

• [ y ] Tests pass
• [ y ] Appropriate changes to documentation are included in the PR

[RoshaniN]

Thanks. A "for future" comment, let's revisit all the xpk args that are not supported by pathways like --debug-dump-gcs, --scheduler etc. and make sure we have bugs for all of those that can be supported with some work.

Yes, thanks for noticing this - I have a backlog item to evaluate these args for Pathways here - b/342189448