Remove time bounds violation fixtures for UCANs that outlive proofs

[bgins]

Summary

Problem

We have some fixtures that are marked as invalid when they expire after their proofs. But a UCAN may be valid for only some capabilities, which means we can't directly correlate time bounds against a single proof.

Impact

The fixtures are invalid and may indicate incorrect information about time bounds. Time bounds should be checked at invocation with the associated proof as context.

Solution

Remove the relevant fixtures.