StorageClass.parameters is immutable and mkfsParams was added after creation,
so every sync failed. Replace=true recreates it instead of patching. Existing
volumes keep their format; only new ones get mkfsParams.
Longhorn names its own disk key and writes storageReserved into it, so git's
default-disk never matched and selfHeal kept trying to add a second disk on the
same path. Dropped spec.disks from git, added ignoreDifferences.