chore(admin-ui): Remove some unused code

admin-ui/src/app/data/client-state/client-types.graphql

@@ -1,10 +1,10 @@
-extend type Query {
+type Query {
     networkStatus: NetworkStatus!
     userStatus: UserStatus!
     uiState: UiState!
 }
 
-extend type Mutation {
+type Mutation {
     requestStarted: Int!
     requestCompleted: Int!
     setAsLoggedIn(username: String!, loginTime: String!): UserStatus!

admin-ui/src/app/data/omit-typename-link.ts

@@ -18,8 +18,4 @@ export class OmitTypenameLink extends ApolloLink {
             return forward ? forward(operation) : null;
         });
     }
-
-    private omitTypename(key: string, value: string): string | undefined {
-        return key === '__typename' ? undefined : value;
-    }
 }