gh-107710: Speed up logging.getHandlerNames function (#107711)

Author: sobolevn

Lib/logging/__init__.py

@@ -916,8 +916,7 @@ def getHandlerNames():
     """
     Return all known handler names as an immutable set.
     """
-    result = set(_handlers.keys())
-    return frozenset(result)
+    return frozenset(_handlers)
 
 
 class Handler(Filterer):

Misc/NEWS.d/next/Library/2023-08-07-14-24-42.gh-issue-107710.xfOCfj.rst

@@ -0,0 +1 @@
+Speed up :func:`logging.getHandlerNames`.