sylva-units: make the default storage class immutable
Consider the following scenario:
- platform starts with a given setup, automatic computation of
_internal.default_storage_classin ylsva-units results in one SC being chosen - PVs are created
- then stuff is done on the platform (enabling a CSI unit) and the computation of default_storage_class leads to something different
- ... only new PVs would use the new class
- the old PVs will not be migrated
This is a bad pattern, "not declarative".
The fix would be to:
- make _internal.default_storage_class immutable
- in the case where the computation of
_internal.default_storage_classleads to something different from before, the immutability check will fail, and the user will have to explicitly setdefault_storage_classto the old value to get back to a working setup (he will do this via #2360 (closed))
/cc @cristian.manda @feleouet @mohan.l.sharma @sakuchoudhary98