move funcional tests back into _test files

[ychebotarev]

What changed?

"merge" test files. Instead of all test functions in xxxx.go and actual test execution xxx_test.go everything is in xxxx_test.go

Why?

This remove a lot of pain for internal developement, and will allow us to make an improvements to our functional testing process.

How did you test it?

by running tests

Is hotfix candidate?

No

[bergundy]

Didn't look in too much depth. Assuming the tests stayed as-is. I would like to understand the impact on test duration with this setup.

[dnr]

can we do this with one PR that is pure code movement and nothing else (that we don't have to look at carefully), and all other changes including lint in another PR (that we have to actually review)?