Remove @python2-only third party stubs that aren't also dependencies (#5975)

Closes #5969

pyrightconfig.json

@@ -8,13 +8,8 @@
         // Python 2 only modules.
         "**/@python2",
         "stubs/enum34",
-        "stubs/fb303",
         "stubs/futures",
-        "stubs/ipaddress",
-        "stubs/kazoo",
-        "stubs/pathlib2",
-        "stubs/pymssql",
-        "stubs/scribe",
+        "stubs/ipaddress"
     ],
     "typeCheckingMode": "basic",
     "strictListInference": true,