gossipsub: Re-write tests to remove technical debt

[thomaseizinger]

With #3327, we took out some technical debt to move forward with #2824. The tests which currently depend on ConnectionId should be refactored to spin up a Swarm and establish an actual connection which will then allow us to remove ConnectionId::DUMMY.

[thomaseizinger]

When tackling this issue, search the codebase for the issue number.

[dgarus]

@thomaseizinger
Hello, Thomas!

I tried to find a comment with the issue number, but couldn't.
Is something changed?
I would like to try to make this issue.

Thanks!

[thomaseizinger]

Thanks for wanting to tackle this!

You can also search for all usages of ConnectionId::DUMMY, that should you lead to the same code places that need fixing!

[thomaseizinger]

Usages of ConnectionId::DUMMY are being replaced in #3652. We still want to rewrite those tests to create Swarms instead though.