gitaly: Embed git binaries

gitaly now embeds git binaries in itself during the build

https://gitlab.com/gitlab-org/gitaly/-/blob/10fd91391a7c30ca54ec81eea881740cfdee8b0a/packed_binaries.go#L22

These are meant to be built by the `Makefile` target
`install-bundled-git` but this produces binaries with different names,
and we're also referring to this version of git throughout the NixOS
module, so we hack this by copying over the binaries from the deprecated
`git` target with which we're building gitaly-git.

(cherry picked from commit b5315bf)

pkgs/applications/version-management/gitlab/gitaly/default.nix

@@ -47,6 +47,9 @@ buildGoModule ({
   preConfigure = ''
     mkdir -p _build/bin
     cp -r ${auxBins}/bin/* _build/bin
+    for f in ${git}/bin/git-*; do
+      cp "$f" "_build/bin/gitaly-$(basename $f)";
+    done
   '';
 
   outputs = [ "out" ];