Actual Implementation of verifySignedRequest Not Tested Due to Stubbing

[akhileshthite]

Currently, in our tests for the ActivityPubSystem, by stubbing the method aps.verifySignedRequest, we're bypassing its actual implementation and immediately returning a resolved promise with a predefined value. This means the real logic of verifySignedRequest is never executed during the test.

• We should only stub fetch and use a regular store and keep all the other apis as is if possible.

Revisit the tests after M3