Add E2E test for cilium network policies as part

Description of the test

Add E2E test for cilium network policies as part of the threat management page. The policies can be seen as listed under the policy tab.

With the removal of cluster application from the UI, ingress had to be installed from the backend in addition to cilium.

Test case issue: gitlab-org/quality/testcases#1855

E2E main issue: #300838 (closed)

Final assertion

Rspec output

Check-list

• 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).
• Ensure that a created resource is removed after test execution. A Group resource can be shared between multiple tests. Do not remove it unless it has a unique path. Note that we have a cleanup job that periodically removes groups under gitlab-qa-sandbox-group.
• 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 with and without the GITLAB_QA_ADMIN_ACCESS_TOKEN provided.