TT#37113 Lower the debug level of 'FLUSH PRIVILEGES'

There are a lot of flushing privileges so in order not to flood the
console move it to debug level.

Change-Id: I98e3247881393d7892799cc23c2a4e5dc865185a

sbin/ngcp-sync-grants

@@ -342,7 +342,6 @@ sub grants_helper {
     my $user = $TEMP_GRANT_USER;
     my $host = $TEMP_GRANT_HOST;
 
-    flush_privs();
     set_user_protected_password($user, $host);
     $dbh->do("REVOKE ALL PRIVILEGES, GRANT OPTION FROM '$user'\@'$host'");
 
@@ -456,7 +455,7 @@ sub check_grants {
 }
 
 sub flush_privs {
-    log_info("flush privileges");
+    log_debug("flush privileges");
     $dbh->do("FLUSH PRIVILEGES")
         or die "Cannot flush privileges: ".$DBI::errstr;