Remove Tharsis integration tests that don't work

[jbowen93]

A lot of the existing integration tests we inherit by forking Tharsis/ethermint won't work because they assume you can start an Ethermint chain with just the ethermintd binary. When using Optimint we need the underlying DA layer to be present to we need to use github.com/celestiaorg/ephemeral-cluster to run integration tests.

Because of this we should remove the GH actions that run the Tharsis integration tests since they'll always fail and replace them with appropriate tests using the ephemeral-cluster.

This includes:

• test-solidity
• liveness-test
• test-rpc