Time based test that can randomly fail

[aeqz]

Clarification and motivation

We have experienced some random CI test failure because of a non-deterministic test in Test.Xrefcheck.TooManyRequestsSpec with the following result:

Expected time to completion be within range (seconds): 3 <= x <= 4, but instead it's 2+999682443/1000000000s

Although this does not happen with so much frequency, we should try to prevent it.

Acceptance criteria

This test case expectation and similar ones in the project have been modified to prevent such error from randomly happen.