Change debug printing to log filename

When restarting the cluster fails the code introduced in 3377497
printed the full log contents to aid debugging.  For cases when the
logfile is large this adds unnecessary overhead.  Reduce to printing
the logfile path instead.

Reported-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20240406214439.2n4zf2w7ukhf7dsy@awork3.anarazel.de

Author: danielgustafsson

src/test/perl/PostgreSQL/Test/Cluster.pm

@@ -951,8 +951,8 @@ sub start
 
 	if ($ret != 0)
 	{
-		print "# pg_ctl start failed; logfile:\n";
-		print PostgreSQL::Test::Utils::slurp_file($self->logfile);
+		print "# pg_ctl start failed; see logfile for details: "
+		  . $self->logfile . "\n";
 
 		# pg_ctl could have timed out, so check to see if there's a pid file;
 		# otherwise our END block will fail to shut down the new postmaster.
@@ -1090,8 +1090,8 @@ sub restart
 
 	if ($ret != 0)
 	{
-		print "# pg_ctl restart failed; logfile:\n";
-		print PostgreSQL::Test::Utils::slurp_file($self->logfile);
+		print "# pg_ctl restart failed; see logfile for details: "
+		  . $self->logfile . "\n";
 
 		# pg_ctl could have timed out, so check to see if there's a pid file;
 		# otherwise our END block will fail to shut down the new postmaster.