Fix tracking property on invite members link

What does this MR do?

• Fixes the track-property to use a cookie based solution instead of going off the current_user.

  • This will ensure we align with our use of the experiment_enabled? call in invite_members_url.

  • Before this change, our track-property did not align with our toggling of the presence of icon or not in the dropdown link. This would lead to incorrect assumptions since we are using track-property to know if the icon was being shown or not.

• Fixes the rollout issue link in the yml

Note no changelog since this is behind an experiment.

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