Add toggle_removal_ticket annotation

[robrap]

Add annotation for toggle_removal_ticket to make it simpler to know if a toggle has an associated DEPR or removal ticket.

Additional notes:

• This will be an optional annotation, at least to start.
• Thoughts for documentation enhancements:
  • The link could be to a DEPR or another ticket.
  • Ideally it would not be a private ticket, but maybe that is ok if the removal is part of the same ticket used to introduce the toggle and it will be very short-lived?
    • In this case (or all cases?), all information that would support the removal should be added to the description or warning annotation.
    • We should note that for temporary rollout toggles, we should document the intended final value. Note that the toggle default might change as part of the rollout, which means it won't always just be the opposite.

This ticket was spun out of #283, which listed a number of potential improvements.

[Yagnesh1998]

assign me

[robrap]

See https://github.com/openedx/code-annotations/blob/764c306d859036971177457cb08cc04e7ee2989c/code_annotations/contrib/config/feature_toggle_annotations.yaml

[robrap]

@Yagnesh1998: Here are the steps I imagine for this ticket:

• Add the new annotation definition for the annotation toggle_removal_ticket to feature_toggle_annotations.yaml.
  • This is mostly just adding: - ".. toggle_removal_ticket:": optional: true (using same formatting of other annotation definitions).
• Update how-to documentation with instructions on how to use the annotation toggle_removal_ticket.
  • See description for documentation notes.
• Lastly, we need to start using this new annotation in the annotation documentation for existing toggles:
  • We could search for toggles with toggle_tickets annotation and toggle_use_cases: temporary?
    • If the toggle_tickets includes a removal ticket on github (e.g. a DEPR ticket), we could remove the link from toggle_tickets and add it to toggle_removal_ticket. If toggle_tickets is now empty, we would delete it because it is optional.
    • If the toggle does not have a toggle_removal_ticket, but needs one, we could add toggle_removal_ticket: TODO.
  • We could go through each DEPR on github and search the code for the DEPR's github issue URL.