Make mysql 8.0 work and support it (this depends on rails upgrade, THREESCALE-1605)

Dev notes

https://github.com/brianmario/mysql2/issues/990

Seeing this GH issue above, it looks like the minimum version of mysql2 gem is 0.5.2
Need to investigate which minimal version of activerecord is supporting this mysql2 gem. And upgrade rails accordingly

QE notes

There is an issue when testing with registry.access.redhat.com/rhscl/mysql-80-rhel7 database image

ERROR 2059 (HY000): Authentication plugin 'caching_sha2_password' cannot be loaded: /usr/lib64/mysql/plugin/caching_sha2_password.so: cannot open shared object file: No such file or directory

Resolution

https://bugs.mysql.com/bug.php?id=90437

Upgrade the mysql client lib in the system image

Dev Notes.

TL;DR
It is due to incompatibilities with RHEL7 https://access.redhat.com/documentation/en-us/red_hat_software_collections/3/html/3.2_release_notes/chap-migration#sect-Migration-MySQL-Changes

So we can solve it by:
1. Migrate system container to RHEL8 which hramihaj does not think we can right now
2. Or mysql server should start with --default-authentication-plugin=mysql_native_password