SpringBoot Upgrade to R2DBC H2 1.1.0.RELEASE

As r2dbc-h2 is not compatible with the latest H2 release, we're stuck upgrading as it's heavily used in our test suite. This issue is about migrating those tests to a different database (which probably means we'll need to move them to docker-based tests).

Comment From: snicoll

Thanks to @mp911de we have now a 1.1.0.BUILD-SNAPSHOT that works against the latest H2 release. I've updated the scope of this issue accordingly.