Reduce time for test_contract_state_cleanup.py integration test

[kevindeforth]

The python test checking if the state clearance triggered by calls to sign, respond or remove_timed_out_requests takes a long time, because it has to wait for the Promise error to be triggered after the default timeout.

This takes roughly five minutes, which is why the test is currently excluded from ci.

The testing time could be reduced with one of the following options (non-exhaustive):

• somehow shorten the protocol timeout for promies_yield_resume during this test (not sure if possible)
• somehow track signature responses submitted to the contract and ensure they failed instead of waiting for the PromiseError.