lvconvert: prevent non-synced raid1 primary leg repair

lvconvert: prevent non-synced raid1 primary leg repair

(Automatic) repair may not be allowed during the initial sync of an upconverted
linear LV, because the data on the failing, primary leg hasn't been completely
synchronized to the N-1 other legs of the raid1 LV (replacing failed legs during
repair involves discontinuing access to any replaced legs data, thus preventing
data recovery on the primary leg e.g. via dd_rescue).

Even though repair would not cause data loss when adding legs to a fully synced
raid1 LV, we don't have information yet defining this state yet (e.g. a raid1
LV flag telling the fully synchronized status before any legs were added),
hence can't automatically decide to allow to repair.

If nonetheless a repair on a non-synced raid1 LVs is intended, the "--force"
option has to be provided.

Resolves: rhbz1311765