Log missing l param for WKD requests, return 400

spec/requests/web_key_directory_spec.rb

@@ -10,9 +10,9 @@ RSpec.describe "OpenPGP Web Key Directory", type: :request do
   end
 
   describe "omitted 'l' param" do
-    it "returns a 404 status" do
+    it "returns a 400 status" do
       get "/.well-known/openpgpkey/hu/fmb8gw3n4zdj4xpwaziki4mwcxr1368i"
-      expect(response).to have_http_status(:not_found)
+      expect(response).to have_http_status(:bad_request)
     end
   end