Switch integration tests to new NXRuntimeTestCase scheme

We have lots of integration tests using either the old and deprecated deployContrib("myresource.xml") or the previous bundle lookup method of NXRuntimeTestCase, e.g, deployBundle("nuxeo-platform-seach-api").

The current lookup scheme is now documented in the nuxeo-book (end of Nuxeo Runtime chapter). This ticket is a long living one, here to track the related checkins.

Maybe we could close it and make a new one each time a release is been made. It's matter of taste if we want this to appear in release notes.