Review Spring Batch auto-configuration now that spring-jdbc is a required dependency

[wilkinsona]

In Batch 5, spring-jdbc is now a required dependency (it was previously optional). We should review the auto-configuration to see if there are any simplifications to be made as we no longer need to support situations where Batch is on the classpath and spring-jdbc is not.

[wilkinsona]

I didn't do a very good job of explaining this. If JobLauncher is on the classpath, DatabasePopulator will now be there too as spring-batch-core now has a compile-scoped dependency on spring-jdbc. As a result, we can review the auto-configuration to remove conditions that check for spring-jdbc.

[wilkinsona]

As @mbhave has pointed out, it's worth checking that spring-jdbc hasn't been excluded so a top-level class condition for a Spring JDBC class makes sense.