* Fixes galera.galera_bf_kill_debug test case.
* Enable galera_ssl_upgrade, galera_ssl_reload, galera_pc_bootstrap
* Add MDEV to disabled tests that miss it

P.S. This commit contains additional changes compared
to the similar commit for 10.5 branch.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>