Draft: Fixing the flaking test

What does this MR do?

Refactors features/projects/ci/lint_spec.rb to move us one step further in fixing the flakiness from #297782 (closed). Also fixes the wrong selector for the editor's content input field.

⚠ The changes in editor_lite.vue are here only to illustrate that things do get stored in the Editor Lite, but the real issue is that somehow valid content does not get validated in the tests 🤷

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #297782 (closed)