JpaTransactionManager not created when needed

[dsyer]

Commit d39a836 added a @Conditional guarding the JpaTransactionManager but failed to take into account the possibility that a DataSourceTransactionManager might already have been autoconfigured.

I can see a test for this already and it passes, so need to do some more research on what happened here.

[dsyer]

The DataSourceTransactionManager is actually created in Spring Batch. You can override this behaviour by adding a custom BatchConfigurer. We can look into doing that in Boot automatically.