Avoid running GetDisplayNameTests in parallel

[tlakollo]

There seems to be a race condition on Cecil while trying to get GenericParameters, if a multithreaded test asks simultaneously about GenericParameters on the same type Cecil answers could vary creating test failures.
Fixes #2693

[sbomer]

Thank you!

[marek-safar]

Do you know which Cecil piece is causing this?

[tlakollo]

Given that the problematic code in linker is https://github.com/dotnet/linker/blob/main/src/linker/Linker/TypeReferenceExtensions.cs#L43-L58
We could assume that is likely caused because the count of genericParametersCount or declaringTypeGenericParametersCount was incorrect. Causing the code to go to the else statement and print the incorrect type.
That would make https://github.com/mono/cecil/blob/main/Mono.Cecil/IGenericParameterProvider.cs#L46-L56 in Cecil the possible cause. Given that is likely that the problem will go away while debugging the bug would need to be found only by code inspection. Spending a few min looking at the code there, it seems to be like it should run fine, so it might be something subtle.