Revert "MDEV-30186 Use of uninitialized value in substitution"

This reverts commit 0e737f78.

As noted by Andrew, this introduces race conditions in the setting
and using of the global $test_name_for_report.

mysql-test/mariadb-test-run.pl

@@ -145,7 +145,6 @@ my $opt_start_exit;
 my $start_only;
 my $file_wsrep_provider;
 my $num_saved_cores= 0;  # Number of core files saved in vardir/log/ so far.
-my $test_name_for_report;
 
 our @global_suppressions;
 
@@ -516,13 +515,13 @@ sub main {
   }
 
   if ( not @$completed ) {
-    if ($test_name_for_report)
-    {
-      my $tinfo = My::Test->new(name => $test_name_for_report);
-      $tinfo->{result}= 'MTR_RES_FAILED';
-      $tinfo->{comment}=' ';
-      mtr_report_test($tinfo);
-    }
+    my $test_name= mtr_grab_file($path_testlog);
+    $test_name =~ s/^CURRENT_TEST:\s//;
+    chomp($test_name);
+    my $tinfo = My::Test->new(name => $test_name);
+    $tinfo->{result}= 'MTR_RES_FAILED';
+    $tinfo->{comment}=' ';
+    mtr_report_test($tinfo);
     mtr_error("Test suite aborted");
   }
 
@@ -3741,8 +3740,8 @@ sub resfile_report_test ($) {
 sub run_testcase ($$) {
   my ($tinfo, $server_socket)= @_;
   my $print_freq=20;
-  $test_name_for_report= $tinfo->{name};
-  mtr_verbose("Running test:", $test_name_for_report);
+
+  mtr_verbose("Running test:", $tinfo->{name});
   $ENV{'MTR_TEST_NAME'} = $tinfo->{name};
   resfile_report_test($tinfo) if $opt_resfile;
 
@@ -5131,10 +5130,12 @@ sub mysqld_start ($$) {
   if (!$rc)
   {
     # Report failure about the last test case before exit
-    my $tinfo = My::Test->new(name => $test_name_for_report);
+    my $test_name= mtr_grab_file($path_current_testlog);
+    $test_name =~ s/^CURRENT_TEST:\s//;
+    my $tinfo = My::Test->new(name => $test_name);
     $tinfo->{result}= 'MTR_RES_FAILED';
     $tinfo->{failures}= 1;
-    $tinfo->{logfile}=get_log_from_proc($mysqld->{'proc'}, $test_name_for_report);
+    $tinfo->{logfile}=get_log_from_proc($mysqld->{'proc'}, $tinfo->{name});
     report_option('verbose', 1);
     mtr_report_test($tinfo);
   }