nginx: disable zstd (#611)

Should not be enabled by default because important fixes are not getting
merged. Trying to figure out that zstd is the culprit is tedious.
Enabling the zstd module breaks SSI (used by jitsi-meet) and home-assistant.

nixos/mixins/nginx.nix

@@ -15,7 +15,6 @@
     recommendedOptimisation = lib.mkDefault true;
     recommendedProxySettings = lib.mkDefault true;
     recommendedTlsSettings = lib.mkDefault true;
-    recommendedZstdSettings = lib.mkDefault true;
 
     # Nginx sends all the access logs to /var/log/nginx/access.log by default.
     # instead of going to the journal!