test: add BLS signature failure tests to eth2-client (#954) #1050

Job	Run time
test eth-prover	42s
test eth2-client	38s
test eth2near/eth_rpc_client	34s
test eth2near/finality-update-verify	38s
test eth2near/contract_wrapper	47s
test eth2near/eth2-contract-init	49s
build rust contracts	44s
test eth2near/eth2-to-near-block-relay-rs	31s
	5m 23s

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