The Hydra build of the libreoffice-collabora derivation introduced in
ab5bdfd3c6 ("libreoffice-collabora: init at 24.04.5-4") fails with the
status "Output limit exceeded" [1], particularly at fetchgit of its
sources. Indeed, the full checkout of the git repo along with its
submodules takes 4.2 GB which is past the 3.4 GB Hydra's max_output_size
[2]. Unfortunately, the Collabora branch lacks the tarball releases
like the upstream fresh/still variants, so we still have to fetch these
submodules. This commit gives up on the usage of fetchSubmodules and
instead fetches the submodules using separate fetchgit calls. This
makes the structure of the nix expression for the collabora variant
closer to the fresh/still variants than the initial version of the
collabora variant.
[1]: https://hydra.nixos.org/build/267358376
[2]: 4b5dd4f974/build/hydra.nix (L51)
f31b6e87b7