client: canonicalize alloc.Job on restore

There is a case for always canonicalizing alloc.Job field when
canonicalizing the alloc.  I'm less certain of implications though, and
the job canonicalize hasn't changed for a long time.

Here, we special case client restore from database as it's probably the
most relevant part.  When receiving an alloc from RPC, the data should
be fresh enough.

client/state/state_database.go

@@ -209,6 +209,7 @@ func (s *BoltStateDB) getAllAllocations(tx *boltdd.Tx) ([]*structs.Allocation, m
 
 		// Handle upgrade path
 		ae.Alloc.Canonicalize()
+		ae.Alloc.Job.Canonicalize()
 
 		allocs = append(allocs, ae.Alloc)
 	}