Change use_super_read_only default back to false

This is because when this flag is true you may not be able to restart a
replica/rdonly vttablet process. This is because:
  1. The tablet has enabled super_read_only in its mysqld because it's
     a replica tablet.
  2. When a tablet starts up, it attempts to run some DDL statements as
     the DBA user such as CREATE DATABASE IF NOT EXISTS _vt and that
     will fail with an error because the mysqld has super_read_only
     enabled.
  3. So the tablet will not be able to come back up properly.

We really should be enabling super_read_only, both in the config file
and in the tablet via this flag, as without that we will in some
cases allow errant GTIDs to be generated which are then lying in wait
to cause later issues. We will enable it at both layers as part
of adding full super_read_only support to Vitess in (which is
targeted for v15):
  vitessio#10363

Signed-off-by: Matt Lord <[email protected]>

go/flags/endtoend/flags_test.go

@@ -1388,7 +1388,7 @@ max_rate_approach_threshold: 0.9
   --unhealthy_threshold duration
 	replication lag after which a replica is considered unhealthy (default 2h0m0s)
   --use_super_read_only
-	Set super_read_only flag when performing planned failover. (default true)
+	Set super_read_only flag when performing planned failover. (default false)
   --v value
 	log level for V logs
   --version

go/vt/vttablet/tabletmanager/rpc_replication.go

@@ -40,7 +40,7 @@ import (
 
 var (
 	enableSemiSync   = flag.Bool("enable_semi_sync", false, "Enable semi-sync when configuring replication, on primary and replica tablets only (rdonly tablets will not ack).")
-	setSuperReadOnly = flag.Bool("use_super_read_only", true, "Set super_read_only flag when performing planned failover.")
+	setSuperReadOnly = flag.Bool("use_super_read_only", false, "Set super_read_only flag when performing planned failover.")
 )
 
 // ReplicationStatus returns the replication status