Fix database migration for MySQL

[itsouvalas]

When using external mysql database the following error is logged:

Starting Liquibase at 11:50:14 (version 4.9.1 #1978 built at 2022-03-28 19:39+0000)
Running Changeset: databasechangelog-primarykey.yml::1::aqan213
Unexpected error running Liquibase: Migration failed for change set databasechangelog-primarykey.yml::1::aqan213:
     Reason: liquibase.exception.DatabaseException: Multiple primary key defined [Failed SQL: (1068) ALTER TABLE autoscaler.DATABASECHANGELOG ADD PRIMARY KEY (id, author, filename)]

Checking the database we do see the primary keys:

and the change to be executed at least once:

Though the constraint name is PRIMARY

This is already disccussed here

With that in mind, the following change updates the preConditions to match on PRIMARY instead of PK_DATABASECHANGELOG. Subsequent deploys honour that and go through fine.

[silvestre]

/easycla

[silvestre]

Unfortunately we currently don't run the acceptance tests with MySQL/MariaDB. We will work on that.

Apart from that, LGTM.

[silvestre]

Running acceptance tests via #718 - will merge this one once it passes.

[silvestre]

The acceptance successfully passed on

using the cherry-picked commits from this PR.