Use error assertion in ica host execution tests

[colin-axner]

Summary

Currently missing code coverage for a message failing validate basic, see here. A test case should be added to ensure that check remains there

Edit: ValidateBasic is being called twice. Once by SDK and once by ibc-go, so adding a test case to fail in ibc-go isn't possible. Instead we can change the OnRecvPacket test to use error assertion, so if both checks are removed, the test fails error is assertion

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[colin-axner]

ref #3778