actor_paft 250 x 10 x 8

Summary:
buck run fbcode//monarch/examples/meta/paft:actor_paft -- --mesh_type thread --group_size 250 --max_groups 10 --min_healthy 7

Rollback Plan:

Differential Revision: D78917462

Author: thomasywang

monarch_hyperactor/src/config.rs

@@ -16,5 +16,5 @@ use hyperactor::attrs::declare_attrs;
 // Declare monarch-specific configuration keys
 declare_attrs! {
     /// Use a single asyncio runtime for all Python actors, rather than one per actor
-    pub attr SHARED_ASYNCIO_RUNTIME: bool = false;
+    pub attr SHARED_ASYNCIO_RUNTIME: bool = true;
 }