Stop binding Flyway directly to the environment

[snicoll]

FlywayCalback is deprecated. We should also deprecate it as we're handling both Callback and FlywayCallback at the moment.

See also #14775

[wilkinsona]

I thought about this when I implemented the upgrade and I'm not sure that we need to do anything more. If someone uses FlywayCallback they'll get the deprecation warning from Flyway. Migrating to Callback, as the warning from Flyway recommends, will resolve the problem. What did you have in mind, @snicoll?

[snicoll]

Flagging the property as deprecated in the metadata and move any test that uses that stuff to @Deprecated so that we can identify those easily when start 2.2.

I used the wrong issue type again, should have been task, sorry.

[snicoll]

So both setter are deprecated and that's for the better as they allow you to specify an instance and there's no way you can do that via application.properties.

See also flyway/flyway#2169

I think we should reconsider stop binding Flyway directly to the environment as we contribute properties users can't use.

[wilkinsona]

Furthermore, all (most?) of the setters on Flyway have been deprecated in favour of working with either FluentConfiguration or ClassicConfiguration. See flyway/flyway#1928.