Add CI Check to flag manually modified cassettes

[ryan-mcneil]

Description

Manually modifying cassettes for requests external services can lead to issues in Production, as the request has not been validated against the service. An engineer may make changes to a cassette with assumptions about how it should work, but without re-recording, they cannot be 100% confident in the behavior. We should create a CI check that runs against modified cassettes, and throws an error if something in the diff seems abnormal

Tasks

• [ ] Create CI Check/GA that checks against a few criteria to help suss out manual edits
  • Check recorded_at date
  • confirm content-length matches the recored request/response body
  • other criteria (?)

Acceptance Criteria

• [ ] Check has been tested against both manually edited and re-recorded cassette
• [ ] Check has been enabled in GH and functions as expected

[rmtolmach]

Another idea:

• On any modified (not new or deleted) vcr cassette, the GHA posts a message to the PR. A warning ⚠️ about the dangers of hand-editing cassettes. And the benefits of re-recording. And a link to any documentation we have about recording cassettes.