MariaDB now defaults to a root db user with a `root` password, but install scripts assume empty password

[jazzsequence]

WPUnit tests installed via WPUnit helpers will fail because the default db user requires a password now. A workaround I've implemented in Pantheon HUD is adding a step that changes the password back to empty:

      - name: Reset MariaDB root password to empty
        run: |
          until mysqladmin ping -h127.0.0.1 -uroot -proot --silent; do
            sleep 1
          done
          mysql -h127.0.0.1 -uroot -proot <<'SQL'
            ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '';
            FLUSH PRIVILEGES;
          SQL
          mysqladmin ping -h127.0.0.1 -uroot --silent

This is a fine band-aid, but ideally this should be handled in WPUnit Helpers. However, I don't like making an update that makes something less secure (even though, arguably, a known password vs an empty password is sort of sixes in terms of actual security for a database environment that's going to be torn down anyway), so I propose:

• implementing the workaround into a new minor point release of the package
• creating a major version release in which use_empty_db_password is a flag that can be toggled
• additionally, allow db_root_pw to be a flag that can be set
• set the default root db password to root
• integrate those steps into the scripts to pull the db password from the passed parameters
• create a major version bump for the behavior change

[jazzsequence]

yes...this is both a bug and an enhancement. it's a bug-hancement.

[jazzsequence]

Looking again at the source, it looks like we already have a --dbpass flag that can be set. so the better workaround for the currently failing workflows is updating the individual install scripts (likely in composer.json files) to pass along --dbpass=root). I still think it's a major version bump because it's changing behavior but we might be able to resolve simply by setting the default password to root instead of an empty string