Fix (preliminary?) for Bug#41502 - MTR v2 should not load plugins during server bootstrap.

Adding --loose-skip-falcon option to the mysqld options provided by MTR (v2) during mysqld bootstrap in order to avoid plugin (in this case Falcon) initialization of static variables etc. Options --loose-skip-innodb and --loose-skip-ndbcluster were already included.

This will fix Bug#41014 (falcon_bug_39708 fails in pushbuild in 6.0-rpl: "succeeded - should have failed")
in the case of MTR v2 (which currently is available in -rpl branches only). 
MTR v1 (e.g. in main 6.0 branch) does not have this problem.

It would be more ideal to remove the --loose-skip-* options and provide a single option disabling all plugin initialization instead, or have bootstrap do this by default. Server modifications are (most likely) needed to be able to do that.

mysql-test/mysql-test-run.pl

@@ -2544,6 +2544,7 @@ sub mysql_install_db {
   mtr_add_arg($args, "--basedir=%s", $install_basedir);
   mtr_add_arg($args, "--datadir=%s", $install_datadir);
   mtr_add_arg($args, "--loose-skip-innodb");
+  mtr_add_arg($args, "--loose-skip-falcon");
   mtr_add_arg($args, "--loose-skip-ndbcluster");
   mtr_add_arg($args, "--tmpdir=%s", "$opt_vardir/tmp/");
   mtr_add_arg($args, "--core-file");