Bug #48133 MTR should not dump entire history of mysqld log when failing to start server

Don't print entire log, but use extract_server_log() introduced by 46007

mysql-test/mysql-test-run.pl

@@ -4702,7 +4702,8 @@ sub start_servers($) {
       my $logfile= $mysqld->value('#log-error');
       if ( defined $logfile and -f $logfile )
       {
-	$tinfo->{logfile}= mtr_fromfile($logfile);
+        my @srv_lines= extract_server_log($logfile, $tinfo->{name});
+	$tinfo->{logfile}= "Server log is:\n" . join ("", @srv_lines);
       }
       else
       {