Improve sanity tests with other executors based tests

[exu]

Is your feature request related to a problem? Please describe.

As a testkube engineer, I want to be sure that changes in executor code doesn't have impact on testkube API

So we would need to implement a bunch of tests for particular executors:

• [x] postman
• [x] cypress (#2294)
• [ ] k6 (#2417, in review)
• [ ] maven
• [ ] gradle
• [ ] soapui
• [ ] ginkgo
• [ ] artillery.io

All tests should be run against Testkube itself

• UI,
• CLI,
• API

Design test plan first for all components

Split this task to separate ones after planning what should be done

Extend release workflows/create quality workflows to run the tests during release:

• [ ] https://github.com/kubeshop/testkube/issues/2306

[tkonieczny]

One more case:

• Checking parameters and ENVs

[tkonieczny]

• Test sources
• Different checkout options

[rangoo94]

@tkonieczny, is it done? I see that it's marked as done on Testkube Quality project, but it's not done in Testkube, nor the issue is closed.