[Experiment Cleanup] invite_for_help_continuous_onboarding - Invite members for tasks from Learn GitLab

Summary

As per PM & Design conversation we have decided to clean up this experiment. FF is currently disabled

• Experiment results: While the experiment showed a positive impact to paid conversion rates we do not understand impact to invites or team activation. Additionally a main part of this experiment's flow will soon be deprecated once Learn GitLab is no longer a separate project #388970 (closed)
• Experiment key / feature flag name: invite_for_help_continuous_onboarding
• Epic or issue link: gitlab-org/growth/team-tasks#459 (closed)

Changes to implement as part of the roll out to becoming an official part of the product:

Current experiment experience:

• 'Invite modal' with tasks is triggered from Learn GitLab
• Invited users see an issue created within the Learn GitLab project if a task was assigned to them

After we clean up this experiment experience:

We want to remove this experiment.

We only want the default 'invite modal' to trigger from Learn GitLab (no tasks) but this is covered in: #388127 (closed)

Steps

• Determine whether the feature should apply to SaaS and/or self-managed
  • SaaS only
• Determine whether the feature should apply to EE - and which tiers - and/or Core
  • SaaS trial + free
• Determine if tracking should be kept as is, removed, or modified.
  • We want to ensure we understand when the Invite modal is triggered from Learn GitLab to inform baseline performance and feasibility to run future experiments with appropriate runtimes
• Ensure any relevant documentation has been updated.
  • No documentation updates needed
• Consider changes to any feature_category: introduced by the experiment if ownership is changing (PM for Growth and PM for the new category as DRIs)
  • No new categories
• Check to see if the experiment introduced new design assets. Add them to the appropriate repos and document them if needed.
• Optional: Migrate experiment to a default enabled feature flag for one milestone and add a changelog. Converting to a feature flag can be skipped at the ICs discretion if risk is deemed low with consideration to both SaaS and (if applicable) self managed
• In the next milestone, remove the feature flag if applicable
• After the flag removal is deployed, clean up the feature/experiment feature flags by running chatops command in #production channel
• Ensure the corresponding Experiment Rollout issue is updated