Improve code owner E2E spec assertions

Summary

In the qa/specs/features/ee/browser_ui/3_create/repository/code_owners_spec.rb:44, when the code owners container is missing, the assertion is misleading.

Screenshot_2025-01-09_at_12.48.20

The assertion should ideally say the code owners container is missing.

Edited by 🤖 GitLab Bot 🤖