ci(TG-404): split unit and integration test runners

[borys-ihnatyev]

Hey guys here is several improvements dedicated on how we run the tests, essentially what tests do we run.

As per TDD development prospective, I have split integration tests (which tests real api calls with db write) and unit tests (external system calls are mocked) runners.

Why? To increase performance of development. How? Unit tests takes fare more less time to run:

• we do not need connect to db before each test and close connection after each test.
• we do not need to start whole server before each test.

[review-ninja]

Current coverage is 94.45% (diff: 100%)

Merging #86 into master will not change coverage

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