feat(users/flokli/nixos-tvix-cache): re-enable http2 r/8962

With nar-bridge supporting zstd content-encoding, we don't need the
nginx zstd module and can re-enable http2.

We also need to propagate the Accept-Encoding sent by the client to
nar-bridge, so it actually knows it can send zstd.

This reduces the time measured in the microbenchmark from ~13s to this:

```
hyperfine 'rm -rf /tmp/cache; nix copy --from https://nixos.tvix.store/ --to "file:///tmp/cache?compression=none" /nix/store/jlkypcf54nrh4n6r0l62ryx93z752hb2-firefox-132.0'
Benchmark 1: rm -rf /tmp/cache; nix copy --from https://nixos.tvix.store/ --to "file:///tmp/cache?compression=none" /nix/store/jlkypcf54nrh4n6r0l62ryx93z752hb2-firefox-132.0
  Time (mean ± σ):      4.880 s ±  0.207 s    [User: 4.661 s, System: 2.377 s]
  Range (min … max):    4.700 s …  5.274 s    10 runs
```

Change-Id: Id092307423636163ae95ef87ec8fa558b83ce0bb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12835
Reviewed-by: Jörg Thalheim <joerg@thalheim.io>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: Ilan Joselevich <personal@ilanjoselevich.com>

0 files changed, 0 insertions, 0 deletions