chore: update librarian version to v0.42.0 (#14293)

Update librarian version to v0.42.0.

Note: Running `librarian tidy` reordered the `released_version` field
under `java:` across library entries in `librarian.yaml` to match the
struct field declaration order of `JavaLibrary` in
`googleapis/librarian` (`internal/config/language.go`).

### Included Librarian Updates
- googleapis/librarian#7524: chore(main): release 0.42.0
- googleapis/librarian#7489: build(.github/workflows): separate java
integration test into standalone job
- googleapis/librarian#7473: chore(main): release 0.41.0

Author: suztomo