fix: fix flaky unstable network tests

[Erigara]

Context

We have unstable_network tests which are constantly failing in the CI.

Solution

Solutions consist of multiple parts:

• @SamHSmith fix to use only genesis peer as client introduced in #4980
• Remove fixed time polling mechanism in favor of event based solution without fixed timeout
  • Idea is that external timeout is anyway exist which would cut off test execution if it takes too long
• Increase transactions ttl to prevent the case when transaction is expired before end up in the committed block

[Erigara]

Ok, i can see that unstable_network tests passed, but the rest of extra_functional tests are still not working with failure to wait for genesis.

Probably i should apply new async genesis await mechanism for them as well.

[Erigara]

Closing for now in favor of #5087.