Mocked SetTTDBlockClient function for Erigon

[dmitriy-b]

Recently Erigon team has removed totalDifficulty erigontech/erigon#11809 from Block schema

As expected, hive tests fail

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x52d522]

goroutine 67 [running]:
math/big.(*Int).Cmp(0xc0002ae500?, 0x1745608?)
	/usr/local/go/src/math/big/int.go:373 +0x22
github.com/ethereum/hive/simulators/ethereum/engine/helper.CheckTTD({0x1757f08, 0xc0002ae500}, {0x1745598?, 0xc00052c190?})
	/source/helper/helper.go:294 +0xe5
github.com/ethereum/hive/simulators/ethereum/engine/helper.WaitForTTD({0x1757f08, 0xc0002ae500}, 0xc0002d4000?, 0xc00028c420, {0x1745598?, 0xc00052c190?})
	/source/helper/helper.go:310 +0x12d
created by github.com/ethereum/hive/simulators/ethereum/engine/helper.WaitAnyClientForTTD
	/source/helper/helper.go:357 +0x1a5

In this PR I just mocked WaitAnyClientForTTD to fix the build and did not remove all TD related things because we do not know when Nethermind and other clients will remove it. We may wait until the changes will be applied to upstream and use similar way to update it.

Another approach is to use environment variables (in jq simulator) and turn on / turn off such features to specific clients.

As for now, the changes affects ethereum/engine-gnosis-erigon simulator only

[GIgako19929]

gh pr checkout 39