Bug #44561 mtr2 --start-dirty is broken

start-dirty would remove stored procs etc.
Skip the copying back from stored system dir if using --start-dirty

mysql-test/mysql-test-run.pl

@@ -3202,7 +3202,7 @@ sub run_testcase ($) {
     {
 
       # Remove old datadirs
-      clean_datadir();
+      clean_datadir() unless $opt_start_dirty;
 
       # Restore old ENV
       while (my ($option, $value)= each( %old_env )) {
@@ -4503,6 +4503,8 @@ sub start_servers($) {
 
     my $mysqld_basedir= $mysqld->value('basedir');
     if ( $basedir eq $mysqld_basedir )
+    {
+      if (! $opt_start_dirty)	# If dirty, keep possibly grown system db
       {
 	# Copy datadir from installed system db
 	for my $path ( "$opt_vardir", "$opt_vardir/..") {
@@ -4513,6 +4515,7 @@ sub start_servers($) {
 	mtr_error("Failed to copy system db to '$datadir'")
 	  unless -d $datadir;
       }
+    }
     else
     {
       mysql_install_db($mysqld); # For versional testing