[BUG] Fix Ethereum Solvency Slashes

This is the counterpart to !2104 (merged) which addresses the other primary source of observed slash points, due to mismatched solvency observations. This change passes the height to the contract call for vaultAllowance to ensure nodes observe balances at the same height. In combination with the 1 block lag in the PR linked above to avoid discrepancy due to block re-orgs, this should hopefully ensure nodes make the same observations.

I've tested these contract calls manually using the ethereum client with a height in CallContract and it seems to work as expected. Based on current network conditions and the default cache configuration of our ethereum daemons, it seems that we have about 25-30 minutes before a given height is pruned - so if a node's ethereum daemon falls behind by more than that they will fail to make observations at older block heights.