Ability to better detect or override DBEngine

[sbrossie]

Kill Bill constructs an instance of the EmbeddedDB abstract class at runtime based on the configuration: It parses the URI scheme to decide whether the underlying engine should be mysql, postgresql, h2 or some generic engine.

When using a package like aws-secretsmanager-jdbc, where the URI is something like jdbc-secretsmanager:mysql://example.com:3306, this breaks the parsing and we end up with a GenericStandaloneDB instead of the MySQLEmbeddedDB.

Most of the functionality may still work, but it will break the global locking we have inside Kill Bill because the runtimeGlobalLocker is instantiated based on the value of such EmbeddedDB.getDBEngine. As a result we end up with a MemoryGlobalLocker which means that in a normal multi-node production environment, there is essentially no global locking and this can lead to all sort of issues (e.g double invoicing).

[sbrossie]

Proposal:

1. We should at least either WARN or ERR when such MemoryGlobalLocker is being used; perhaps we should even prevent the system from starting unless we have set the org.killbill.server.test.mode property.
2. We could also modify our parsing scheme to allow for secretsmanager:mysql to be set to mysql scheme (i.e look for a 'contains' instead or 'strict equality').
3. Alternatively (or in addition to), we could also add a way to override the engine scheme from the properties exposed in our DaoConfig