Make new auto_explain test safe for log_error_verbosity = verbose.

Allow for the possible presence of a SQLSTATE code in the expected warning message, similarly to b998196 and 19408aa (although here I see no need to allow more than one specific SQLSTATE). Per gripe from Andrew Dunstan. Discussion: https://postgr.es/m/[email protected]

Author: tglsfdc

contrib/auto_explain/t/001_auto_explain.pl

@@ -135,7 +135,7 @@ sub query_log
 
 like(
 $log_contents,
-qr/WARNING: permission denied to set parameter "auto_explain\.log_level"/,
+qr/WARNING: ( 42501:)? permission denied to set parameter "auto_explain\.log_level"/,
 "permission failure logged");
 
 } # end queries run as regress_user1