Automate SSL connection tests for MariaDB

There are various bugs open about TLS connection issues in Debian and Ubuntu:

https://bugs.launchpad.net/ubuntu/+source/mariadb-10.3/+bug/1885632

• MariaDB 10.3 as provided by Ubuntu.org is compiled against YaSSL version 2.4.4, which supports a maximum TLS version of 1.1. The Ubuntu 20.04 release has a minimum TLS 1.2 requirement, rendering all MariaDB TLS connections unusable.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=921151

• appears that the Debian client is only attempting to negotiate a connection with TLSv1.1, which is blacklisted

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=927289

• Apparently YaSSL (now WolfSSL) did not support any other certificate format than PEM, and the error message is uninformative

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=956401

• Option --ssl-verify-server-cert did not work. Possibly because of MDEV-12190: YaSSL's highest supported version is TLSv1.1 (=3.2) - if the client requests a higher version, it needs to be downgraded in Server Hello packet to TLSv1.1 instead of interrupting the handshake and closing the connection.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=956810

• libmariadb3 compiled libdbd-mysql failed to connect to MySQL server that required TLS

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=875457

• clients could not connect using ssl (the error message was: ERROR 2026 (HY000): SSL connection error: protocol version mismatch)

The biggest problem right now is that we don't know the status of these issues.

We should extend the debian/salsa-ci.yml to do a simple TLS scenario and test the connection so we know if it even works in the most basic case.