Replace External Catalogs with Test-Only Mock Catalog for E2E

[camilamacedo86]

Some E2E tests might still rely on external catalogs like Community, which we don't control.

We should create a mock Operator and Catalog for testing and update the tests to use it. This makes tests fully self-contained.

Ref: https://github.com/operator-framework/operator-controller/tree/main/testdata