Use non-privileged user in Ethereum's Dockerfile

[JekaMas]

Problem

The Ethereum issue with docker privileges slows our progress in testing.

Implementation

Resolve ethereum/go-ethereum#15816

Acceptance Criteria

Issue is resolved and merged into Ethereum master.

Part of status-im/swarms#71

[adambabik]

What's the problem with using a privileged user in a docker container?

[fgimenez]

I've already proposed ethereum/go-ethereum#16052 to address this one, still being reviewed though.

[dshulyak]

do we depend on it in any way? looks like that we don't use ethereum containers

i will close it, but feel free to re-open if you feel strongly that we need it.
also even if it is good thing by itself - this is status-go repository :)