Fail build on unnecessary allowed_extra_analytics

[aduth]

🛠 Summary of changes

Builds upon #9946 to enforce that allowed_extra_analytics RSpec example group metadata exactly matches the undocumented parameters discovered in that group.

This helps facilitate a pathway to gradually move away from allowed_extra_analytics and require that all extra analytics are documented.

Related discussion: #10548 (comment)

📜 Testing Plan

Verify that build fails with demonstrated failures in 25f66ab. Build should pass after those changes are reverted (and after any legitimate issues identified by this linter are resolved).

[aduth]

Example failure with changes in 25f66ab:

An error occurred in an `after(:context)` hook.
Failure/Error:
  expect(allowed_extra_analytics).to(
    match_array(all_checked_extra_analytics),
    "Unnecessary allowed_extra_analytics method names on example group #{group}: " +
      (allowed_extra_analytics - all_checked_extra_analytics).to_s,
  )

  Unnecessary allowed_extra_analytics method names on example group RSpec::ExampleGroups::UsersPivCacAuthenticationSetupController: [:foo]

[aduth]

Example failure with changes in 25f66ab:

An error occurred in an `after(:context)` hook.
Failure/Error:
  expect(all_checked_extra_analytics).not_to(
    be_blank,
    "Unnecessary allowed_extra_analytics on example group #{group}",
  )

  Unnecessary allowed_extra_analytics on example group RSpec::ExampleGroups::UsersTotpSetupController

[zachmargolis]

LGTM, would it be good to add a spec to show what this fails like in the fake_analytics_spec.rb?

https://github.com/18F/identity-idp/blob/main/spec/support/fake_analytics_spec.rb#L555

[aduth]

would it be good to add a spec to show what this fails like in the fake_analytics_spec.rb?

It would be good, yeah. I spent a little time looking at it and I'm not entirely sure how to approach it, since the error only happens after tests are run. And the current implementation also assumes that allowed_extra_analytics is defined on the top-level example group of a file, where existing specs in fake_analytics_spec.rb test this as a per-example metadata.

Unsure if you might any ideas, otherwise I think it could be okay to leave untested? Since this is spec-specific behavior anyways, and ideally will be short-lived during a transitionary period.