Update Off-Blocks credentials and test suite tweaks

Updated Off-Blocks credentials to fit with the expectations of the new test suite.

Tweaks to test suite:

• increased timeout to allow for slightly longer async calls
• updated the "removed property" test to delete a credential key in the subject rather than the type key

The second tweak is the only major change. This was necessary as removing the type key should actually result in a 400 error instead of a validation error, as you are no longer sending a valid verifiable credential to the endpoint. By deleting a credential subject property instead, we are still sending a valid credential, but not one containing all information in the signature.