execution engine port "already in use" should be a critical error

[dapplion]

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Is your feature request related to a problem? Please describe.

If port for execution engine is already in use Nethermind just does log and continues. This should be a fatal error and stop the process completely

Instead it just logs this, which is buried in init logs:

el_1  | 2022-06-11 15:04:02.5319|Additional JSON RPC URL 'http://localhost:8551' wants port 8551, but port already in use; skipping...

post-merge this could be really bad for users

Describe the solution you'd like

The process should exit 1 immediately.