Rework test framework (#3271)

- Removes `--auth_with_token` and `auth_with_jwt` pytest options
- Auth modes are set in test code to have self-contained record mode
- Turn static `BasicTestCase` attributes into class attributes, add
setters:
  - per_page
  - retry
  - pool_size
  - seconds_between_requests
  - seconds_between_writes
- Updates documentation (`CONTRIBUTING.md`)

Supersedes #2147.

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Co-authored-by: Prateek <110811408+Prateikx@users.noreply.github.com>