MDEV-33837: Suspend lintian warnings for description is synopsis

Lintian warn that mariadb-common and mysql-common descriptions
are sypnosis as they contain dot but dots are used in other
purposes so they are just false-positives:

 * mysql-common: synopsis-is-a-sentence "MariaDB client common configuration files package (e.g. /etc/mysql/my.cnf)"
 * mariadb-server: unused-debconf-template mariadb-server/old_data_directory_saved [templates:2]

debian/mariadb-common.lintian-overrides

+# This false-positive as is just seeks dot
+synopsis-is-a-sentence "MariaDB database common files (e.g. /etc/mysql/mariadb.conf.d/)"

debian/mysql-common.lintian-overrides

+# This false-positive as is just seeks dot
+synopsis-is-a-sentence "MariaDB client common configuration files package (e.g. /etc/mysql/my.cnf)"