Increase Group Wiki e2e coverage

Description of the test

Issue: #373394 (closed)

• For Create Group Wiki: Edit spec. It turns out a page with Home page title is not a legit home page. We are required to hardcode the 'home' title for it to be a true home-page.
• Add Delete Group Wiki to increase coverage
• Add file Upload Spec as that can usually only be done at E2E level

qa/specs/features/ee/browser_ui/3_create/wiki/create_group_wiki_page_spec.rb: https://gitlab.com/gitlab-org/gitlab/-/quality/test_cases/347689

qa/specs/features/ee/browser_ui/3_create/wiki/delete_group_wiki_page_spec.rb: https://gitlab.com/gitlab-org/gitlab/-/quality/test_cases/374707

qa/specs/features/ee/browser_ui/3_create/wiki/file_upload_group_wiki_page_spec.rb: https://gitlab.com/gitlab-org/gitlab/-/quality/test_cases/375655

Checklist

• Confirm the test has a testcase: tag linking to an existing test case in the test case project.
• Note if the test is intended to run in specific scenarios. If a scenario is new, add a link to the MR that adds the new scenario.
• Follow the end-to-end tests style guide and best practices.
• Use the appropriate RSpec metadata tag(s).
• Most resources will be cleaned up via the general cleanup task. Check that is successful, or ensure resources are cleaned up in the test:
  • New resources have api_get_path and api_delete_path implemented if possible.
  • If any resource cannot be deleted in the general delete task, make sure it is ignored.
  • If any resource cannot be deleted in the general delete task, remove it in the test (e.g., in an after block).
• Ensure that no transient bugs are hidden accidentally due to the usage of waits and reloads.
• Verify the tags to ensure it runs on the desired test environments.
• If this MR has a dependency on another MR, such as a GitLab QA MR, specify the order in which the MRs should be merged.
• (If applicable) Create a follow-up issue to document the special setup necessary to run the test: ISSUE_LINK
• If the test requires an admin's personal access token, ensure that the test passes on your local environment with and without the GITLAB_QA_ADMIN_ACCESS_TOKEN provided.