revisit M6 integration test and verify thoroughly

[brenzi]

Our current tests do not detect failed unshielding because they only test if the funds have been burned on L2, but not if they have arrived at their L1 destination:

worker/cli/demo_shielding_unshielding.sh

Lines 189 to 195 in 868880a

	echo "* Un-shield ${AMOUNT_UNSHIELD} tokens from Alice's incognito account to Ferie's L1 account"
	${CLIENT} trusted --mrenclave ${MRENCLAVE} unshield-funds ${ICGACCOUNTALICE} //Ferdie ${AMOUNT_UNSHIELD}
	echo ""
	echo "* Wait and assert Alice's incognito account balance... "
	wait_assert_state ${MRENCLAVE} ${ICGACCOUNTALICE} balance $(( BALANCE_INCOGNITO_ALICE + AMOUNT_SHIELD - AMOUNT_TRANSFER - AMOUNT_UNSHIELD ))
	echo "✔ ok"