Streamline test pattern

I appreciate that we try to document he test. If we're writing a geherkin-style test scenarios, can we please use recognized way for this?
https://support.smartbear.com/cucumberstudio/docs/bdd/write-gherkin-scenarios.html

_Originally posted by @ezaquarii in https://github.com/nextcloud/android/pull/5465_

--> This should be a discussion, if and how we want to use a test pattern for our tests
I am ok with geherkin-style, but would also be fine with a test description above function and three steps "arrange", "act", "assert", but I guess the geherkin-style is more standardized, which could help us to write clean and simple test cases?

@ezaquarii @AndyScherzinger @Shagequi