Avoid to update inlined relation column to NULL when deleting entities When deleting entities, cubicweb run a rql DELETE on all relations to trigger hooks. For an inlined relation this also mean set the column to NULL. This operation may fail if there's additional constraints on the column. Also this is a weird and useless behavior since deleting the entity row will by definition delete the relation. We still doesn't handle the case where both subject and object are going to be deleted because rows need to be deleted in a particular order that cubicweb doesn't handle. Add a test checking UPDATE does not occur but hooks are correctly called. Closes #17236690

Drop useless ConstraintInsertionTC This test does nothing and is here from the begining of repo history. Now it raise an error "TypeError: Skipped expected string as 'msg' parameter, got 'SkipTest' instead. Perhaps you meant to use a mark?" Just drop it.

Backed out changeset 741dc2590f90 It was for cube s3storage, but this piece of information was apparently not in the email (used for review), so this patch was published in the wrong repository. :-/