Harmonize Local and CI Test(s)-Builds

[Nicoretti]

Description

Currently the tests are executed (started and setup) differently depending if they are run locally or on the CI.
(e.g. The CI uses ITDE for setting up a test DB, Local builds in turn use(d) an undocumented publicly available DB)

To simplify the complexity and the potential sources of errors we should strive to harmonize the build(s) as much as possible.

Ideally the host system (Local, CI) is responsible to provide/setup the host specific dependencies, like system libraries etc. and everything else uses the same execution path/method.

Acceptance criteria

• Cut the dependency to the publicly "available" Test DB
• Simplify local and CI testing by having some sort of task execution (make, tox, nox, ...)
  • test call should look exactly the same on CI and Local builds e.g. python run_tests.py
• Document how to setup and run the test(s)
• Remove outdated description(s) and resources

[Nicoretti]

see #115