Fix fts_unblock_primary answer file.

Remove the extra WARNING only gets generated for MAC.

src/test/isolation2/expected/segwalrep/fts_unblock_primary.out

@@ -156,9 +156,8 @@ t
 -- bring the mirror back up and see primary s/u and mirror s/u
 -1U: select pg_ctl((select datadir from gp_segment_configuration c where c.role='m' and c.content=2), 'start', (select port from gp_segment_configuration where content = 2 and preferred_role = 'm'), 2, (select dbid from gp_segment_configuration c where c.role='m' and c.content=2));
 pg_ctl          
--------------------------------------------------------------------------------------------------------
+----------------
 server starting
-WARNING:  (01000) cpu rate limitation for resource group is unsupported on this system
 
 (1 row)
 select gp_wait_until_triggered_fault('initialize_wal_sender', 1, dbid) from gp_segment_configuration where role='p' and content=2;