drop oci image outputs

We don't support this anyway. OCI images will be needed for testing with
Complement, but there are a bunch of other special requirements that has
so these oci image outputs won't be very useful for that anyway.

nix/pkgs/oci-image/default.nix

@@ -1,25 +0,0 @@
-# Keep sorted
-{ default
-, dockerTools
-, lib
-, tini
-}:
-
-dockerTools.buildImage {
-  name = default.pname;
-  tag = "next";
-  copyToRoot = [
-    dockerTools.caCertificates
-  ];
-  config = {
-    # Use the `tini` init system so that signals (e.g. ctrl+c/SIGINT)
-    # are handled as expected
-    Entrypoint = [
-      "${lib.getExe' tini "tini"}"
-      "--"
-    ];
-    Cmd = [
-      "${lib.getExe default}"
-    ];
-  };
-}