pulp-cleanup: add nightly Jenkins job for stale Pulp resource cleanup

[vamahaja]

Summary

• Add a nightly pulp-cleanup-nightly Jenkins job that purges stale ceph project Pulp repositories and distributions using scripts/purge-policy.yaml.
• Cleanup excludes named policy refs via label-select, deletes remaining resources past the default retention days (distributions before repositories), then runs orphan cleanup.
• Update pulp_upload.sh so repository version retention uses per BRANCH & keep_minimum from the purge policy, with fallback to the default.

Job config

• Job: pulp-cleanup-nightly, triggered @midnight.
• Parameters: CEPH_BUILD_BRANCH (default main), CEPH bool (default true) to enable ceph project cleanup.
• Pipeline sets up the Pulp client, then runs cleanup.sh when CEPH is true.

Purge policy (scripts/purge-policy.yaml)

• Project root: ceph
• Default retention: days: 14, keep_minimum: 3
• Per-ref overrides for release and special branches
• Cleanup uses named refs as exclusions; uploads use keep_minimum for repository version retention

[djgalloway]

I think we need something more like chacra's retention map.

Or at least leave this PR as-is but add KEEP_MINIMUM or RETAIN_MINIMUM on top of RETAIN_DAYS.

[vamahaja]

I think we need something more like chacra's retention map.

Or at least leave this PR as-is but add KEEP_MINIMUM or RETAIN_MINIMUM on top of RETAIN_DAYS.

Updated logic PTAL.