♻️ sync owner migration and facade thinning

src-async/async_logger_native.mbt

@@ -8,18 +8,3 @@ pub fn async_runtime_supports_background_worker() -> Bool {
   ignore(all_async_runtime_modes())
   true
 }
-
-///|
-fn async_runtime_guard_closed_on_log() -> Bool {
-  false
-}
-
-///|
-fn async_runtime_shutdown_clears_pending_after_wait_idle() -> Bool {
-  true
-}
-
-///|
-fn async_runtime_shutdown_waits_for_worker() -> Bool {
-  true
-}