Create another set of tests using `reliable` tag and include all the end-to-end tests for ~devops::plan

Per our discussion in the rapid action, we know right off the bat that the tests for the devopsplan stage is relatively stable. Let's create a new tag called reliable and have these configured to run as part of the release process.

Tasks

• Add reliable tag to gitlab qa test kickoff variables.
• Add all tests for devopsplan gitlab-org/gitlab!24389 (merged)
• Provide the delivery team with this new CLI command to run these tests
• [-] Add documentation and process surrounding the promotion of a test to reliable -> Moved to #378 (closed)

Instructions for running the reliable tests

Use the following command to run the reliable tests from inside the qa/ directory bin/qa Test::Instance::All http://localhost:3000 -- qa/specs/features/ --tag reliable.