To fix this, it is necessary to add an option to exclude the
database with the name "lost+found" from processing (the database
name will be checked by the check_if_skip_database_by_path() or
by the check_if_skip_database() function, and as a result
"lost+found" will be skipped).

In addition, it is necessary to slightly modify the verification
logic in the check_if_skip_database() function.

Also added a new test galera_sst_mariabackup_lost_found.test