Fix block height in storage after epoch change

[sug0]

The block height of a new epoch updated in storage, after we call finalize_block(), is wrong. We need to store the previous height, rather than the next height.

The fix is fairly simple. We just need to apply this patch in reverse.

We also need to fix a related unit test (test_can_send_validator_set_update), or simply #[ignore] it for now.

[sug0]

Linked PR #594
We can just patch eth-bridge-integration with those changes, as well