Detect generic recursion pattern in S.Linq.Parallel (#71802)

Detect generic recursion pattern in S.Linq.Parallel (#71802)

System.Linq.Parallel has multiple generic cycles in it. We probably hit them all in the System.Linq.Parallel.Tests assembly. We would be compiling the test forever (or until running out of memory) because we didn't detect one of them.

Add detection for the case where the recursion is entered through a generic interface virtual method call. The compiler terminates the infinite expansion after the user-specifiable cutoff point.

The test shows the pattern and the expected behavior.