Get more tests running on Windows (#6537)

* Get rid of system() calls

* Work around '/usr/share/mini' showing up on GitHub Actions (probably due to psutil truncation)

https://github.com/ray-project/ray/runs/722480047?check_suite_focus=true

* Don't check for socket max path length on Windows

* Don't check for socket existence on Windows

* Fix race condition in Windows fate-sharing

* Work around missing .exe extension for Redis tests

* Add more tests to GitHub Actions

Co-authored-by: Mehrdad <noreply@github.com>

python/ray/tests/test_metrics.py

@@ -113,9 +113,9 @@ def test_worker_stats(shutdown_only):
         ]
         for process in processes:
             # TODO(ekl) why does travis/mi end up in the process list
-            assert ("python" in process or "conda" in process
-                    or "travis" in process or "runner" in process
-                    or "ray" in process)
+            assert ("python" in process or "mini" in process
+                    or "conda" in process or "travis" in process
+                    or "runner" in process or "ray" in process)
         break
 
     # Test kill_actor.