On-cluster build PersistentVolume fills up across builds

[lkingland]

The PersistentVolume used for on-cluster builds (both standard and
Pipelines-as-Code) is reused across builds without cleanup. Over time
it fills up, causing subsequent builds to fail with "No space left on
device" during git-init.

The build pipeline should clean up or rotate workspace PVs between
builds to prevent accumulation.

Related: SRVOCF-583