revert of sylva-units schema change breaking OCI deployments
This is a revert of prevent having both 'repo' and 'helmrelease_spe... (!2970 - merged) which broke all OCI-based CI jobs.
The change that caused the breakage is !2970 (2533cd43) "sylva-units schema: don't skip checks for 'enabled: false' units".
Ideally, the schema should be strict, in particular adding the checks that it adds in !2970 (merged) on all units including disabled ones. But the way we define units for OCI-based deployments is such that we can't apply all the checks that !2970 (merged) started to apply on units including disabled ones.
Edited by Thomas Morin