Investigate potential usage of tools to detect flaky tests automatically

[NiccoMlt]

Flaky tests have been a problem for too long in this project; take #439 as a reference for details.

In the last couple of days, thanks to @hamadodene many steps further were made to identify and in some cases fix them.

@hamadodene is suggesting to try out tools for automatic flakyness detection in tests, like https://star-rg.github.io/shaker