Fix 20Ti dhstore-data PVC

[ischasny]

PVC dhstore-data in prod is configured as 20Ti, however it's actually 15Ti as AWS doesn't support volumes larger than 16Ti.

The number in file can't be reduced either as then it would fail reconciliation in K8s (because it doesn't support downsizing the volumes).
The only way to fix this - is to move the data to a different PVC, map it to dhstore and delete this one. Snapshot of dhstore-data is already taken in prod.