Add more assignment tests in docker

[alexcojocaru2002]

The aim of this MR is to add more random assignment tests (4) in docker, as per discussed in #236

Closes #251

[alexcojocaru2002]

Also maybe good to note the docker workflow is a bit flaky, not sure why
Between these 2 runs there is no change

[Arraying]

The GH API sometimes rejects requests with invalid user agents, my guess is the ADD fell back to the default HTTP headers which GitHub was unhappy with. @martinmladenov this way of cache invalidation is very strange, perhaps we should create an issue to improve it. Specifically, ADD supports Git repositories natively, mayhaps we can replace the cache-buster and clone with a singular repository ADD.

[martinmladenov]

@Arraying Interesting, I didn't know that, thanks. I saw a stackoverflow post which stated that downloading commit info to break the cache is the best solution. Let's make a new issue.