nixos/redis: unbreak module

The redis module currently fails to start up, most likely due to running
a chown as non-root in preStart.

While at it, I hardcoded it to use systemd's StateDirectory and
DynamicUser to manage directory permissions, removed the unused
appendOnlyFilename option, and the pidFile option.

We properly tell redis now it's daemonized, and it'll use notify support
to signal readiness.

nixos/modules/rename.nix

@@ -256,7 +256,7 @@ with lib;
 
     # binfmt
     (mkRenamedOptionModule [ "boot" "binfmtMiscRegistrations" ] [ "boot" "binfmt" "registrations" ])
-    
+
     # ACME
     (mkRemovedOptionModule [ "security" "acme" "directory"] "ACME Directory is now hardcoded to /var/lib/acme and its permisisons are managed by systemd. See https://github.com/NixOS/nixpkgs/issues/53852 for more info.")
     (mkRemovedOptionModule [ "security" "acme" "preDelay"] "This option has been removed. If you want to make sure that something executes before certificates are provisioned, add a RequiredBy=acme-\${cert}.service to the service you want to execute before the cert renewal")
@@ -285,6 +285,13 @@ with lib;
           throw "services.redshift.longitude is set to null, you can remove this"
           else builtins.fromJSON value))
 
+    # Redis
+    (mkRemovedOptionModule [ "services" "redis" "user" ] "The redis module now is hardcoded to the redis user.")
+    (mkRemovedOptionModule [ "services" "redis" "dbpath" ] "The redis module now uses /var/lib/redis as data directory.")
+    (mkRemovedOptionModule [ "services" "redis" "dbFilename" ] "The redis module now uses /var/lib/redis/dump.rdb as database dump location.")
+    (mkRemovedOptionModule [ "services" "redis" "appendOnlyFilename" ] "This option was never used.")
+    (mkRemovedOptionModule [ "services" "redis" "pidFile" ] "This option was removed.")
+
   ] ++ (forEach [ "blackboxExporter" "collectdExporter" "fritzboxExporter"
                    "jsonExporter" "minioExporter" "nginxExporter" "nodeExporter"
                    "snmpExporter" "unifiExporter" "varnishExporter" ]