End-to-end configuration tests

[lidel]

Rainbow needs end-to-end regression tests that build binary and confirm sensitive configuration is applied correctly:

• [ ] confirm env RAINBOW_TRUSTLESS_GATEWAY_DOMAINS is applied correctly
• [ ] confirm cli param --trustless-gateway-domains is applied correctly

We can't afford regression in trustless-only mode, but once we have end-to-end setup, we cna test more with it.

[hacdias]

I think the trick here is isolating all tests, or not running any E2E tests in parallel.