Drop AboutInfo override for dav4jvm

With the recent move to GitHub, the AboutInfo override for dav4jvm was
broken as it still used com_gitlab_bitfireAT__dav4jvm whereas it is now:
```
$ ./gradlew findLibraries | grep dav4jvm
bitfireAT/dav4jvm (f1d9354a41) -> com_github_bitfireAT__dav4jvm
Manually requested license: mpl_2_0
```

Since the autogenerated dav4jvm AboutInfo looks fine (see attached
screenshot), remove the override.