Lower call stack size for test_big_recursive_cobegin

This recursively creates 1024 tasks, and at the default of 8MB per task that's
8GB of memory. Trying to limit max memory used by correctness tests to under
4GB so I'm lowering the call stack size
Lower call stack size for parallel/taskPool/figueroa/ManyThreads

This recursively creates up to 3000 tasks, and at the default of 8MB per task
that's a lot of memory. I'm trying to limit max memory used by correctness
tests to under 4GB so I'm lowering the call stack size