Remove overeager assertion in logical_heap_begin_rewrite.

It's legal to configure wal_level=logical and max_replication_slots=0
simultaneously.

Andres Freund

src/backend/access/heap/rewriteheap.c

@@ -812,8 +812,6 @@ logical_begin_heap_rewrite(RewriteState state)
 	if (!state->rs_logical_rewrite)
 		return;
 
-	Assert(ReplicationSlotCtl != NULL);
-
 	ProcArrayGetReplicationSlotXmin(NULL, &logical_xmin);
 
 	/*