Agent chat code cleanup (#13088)

This PR addresses feedback from
[PR-13061](https://github.com/twentyhq/twenty/pull/13061).

- Removed redundant type assertion from `apollo.factory.ts`.
- Removed redundant tests: Eliminated test cases that were specifically
added to boost coverage metrics rather than testing meaningful
functionality

packages/twenty-front/src/modules/apollo/services/apollo.factory.ts

@@ -230,7 +230,7 @@ export class ApolloFactory<TCacheShape> implements ApolloManager<TCacheShape> {
           retryLink,
           restLink,
           httpLink,
-        ].filter(isDefined) as ApolloLink[],
+        ].filter(isDefined),
       );
     };