Write a test for web3 gas estimation on new blokchains

[hackaugusto]

Write a test for #3810 that fixes #3244 .

[pirapira]

I reproduced the issue following this procedure: https://github.com/raiden-network/raiden/blob/fe45769dd3c3f339b30a214599d028eb8351dc6a/docs/private_net_tutorial.rst .

[pirapira]

I reproduced the issue following this procedure: https://github.com/pirapira/raiden/blob/be088c233293d7b02fc55e7549950f4da03fe2e3/docs/private_net_tutorial.rst