Test 5-7 tries to delete a PVC at the very same time when it detects that
the PV controller started processing the PVC. The controller then sometimes
can't update the PVC and generate an event for it that the test expects.
From PV controller logs (not shown in CI):
> I1221 14:36:34.548160 104481 pv_controller.go:815] updating PersistentVolumeClaim[default/claim5-7] status: set phase Lost failed: cannot update claim claim5-7: claim not found
Typical error in CI:
> FAIL: TestControllerSync (83.22s)
> framework_test.go:202: Event "Warning ClaimLost" not emitted
Therefore wait for the PVC to be fully processed before deleting the PVC to
avoid races.