[llvm] [utils][tests] Adjust timeout-hang.py tolerances (PR #142089)

[David Spickett via llvm-commits]

================
@@ -8,20 +8,25 @@
 # throwing an exception. We expect this to fail immediately, rather than
 # timeout.
 
-# DEFINE: %{timeout}=1
+# DEFINE: %{grace_period}=5
----------------
DavidSpickett wrote:

I think you need a comment here to explain the logic of this, as it's the sort of test that will fail out of the blue for some people even with this relaxation.

Perhaps:
```
# lit should return immediately once it fails to execute the non-existent program. This will take a variable amount of time depending on process scheduling, but it should always be significantly less than the hard timeout, which is the point where lit would cancel the test.
```

https://github.com/llvm/llvm-project/pull/142089