Remove usage of Lab API for integration test config

[Avery-Dunn]

This PR makes similar changes to what is being done in other MSALs:
AzureAD/microsoft-authentication-library-for-java#1002
AzureAD/microsoft-authentication-library-for-dotnet#5631
AzureAD/microsoft-authentication-library-for-go#593

Historically, integration tests in MSAL and MISE retrieved user/app/tenant/etc. info from our API at "https://msidlab.com/api/"

That API is being deprecated in favor of a key vault-based system: instead of dynamic config based on query parameters, we have a simpler set of config stored as key vault secrets.

This PR refactors the integration tests to retrieve the config they need from those key vaults instead of the API:

• lab_config.py : A new file to contain all of the helper functions, data classes, and constants used by the integration tests
  • Includes a simple cache based on secret name to store the configuration we get from the key vault and avoid repeated calls
• test_e2e.py : Removed helpers that retrieved config from the Lab API and adjusted tests to use the new helpers

The behavior of the tests were not meaningfully changed, except for the following:

• ADFS scenarios: removed tests covering old ADFS versions and replaced them with a new ADFS 2022 test (which is currently skipped, just like the old ADFS tests and similar to how it is in other MSALs)
• Arlington scenarios: removed tests covering CCA scenarios, to give it similar coverage as other MSALs and generally reduce how much we test different clouds
• Added a new helper for cert-based ConfidentialClientApplication instances and adjusted a few tests to use it instead of secrets
• Removed a few environment variable-based conditions (mainly related to OBO) which would skip the test if not set, since we can reliably get that info from the key vault like the other MSALs