Update and restructure TestGCLogMessages log message list

The TestGCLogMessages test case checks for G1 log messages; it registers the expected messages in the test, roughly organizing them by the group they are in.

After the introduction of the batched gang task API, and the related restructuring of the post evacuation phase, it looks like this list has not been updated properly to represent the output.

Also some messages seem to be missing in that list.