Update mythProxy mocks with new changes

[Moliholy]

According to the auditors:

As a small informational note, we suggest using the same filters in the mocks of the myth-proxy pallet as the ones used in the testnet and mainnet for better consistency in the future, especially if more tests will be added. Those filtered calls should ideally match the ones in the mainnet, as well as the ProxyType enum, where the one declared in the mocks differs from the one declared in the mainnet (and the testnet).