Refactor tests not to use unncessary keeper methods #833
Description
Currently some tests code call unnecessary keeper methods and it makes unnecessary keeper dependency to tests.
for example, in staking precompile test, GetERC20Keeper().BalanceOf() is used to get erc20 token balance.
It can be replaced with contract call using GetEVMKeeper().CallEvm().
other example is GetFeeMarketKeeper().BaseFee() usage in gov precmopile keeper.
In this case, we can also use GetEVMKeeper().BaseFee().