Remove unused stubtest allowlist entries (#6119)

Co-authored-by: hauntsaninja <[email protected]>

Author: github-actions[bot]

tests/stubtest_allowlists/py310.txt

@@ -106,9 +106,6 @@ collections.abc.Coroutine.send
 collections.abc.Coroutine.throw
 collections.abc.Generator.send
 collections.abc.Generator.throw
-contextlib.AsyncExitStack.callback
-contextlib.AsyncExitStack.push_async_callback
-contextlib.ExitStack.callback
 contextvars.ContextVar.reset
 contextvars.ContextVar.set
 io.IncrementalNewlineDecoder.setstate
@@ -169,6 +166,5 @@ ssl.SSLContext.__new__
 ssl._create_unverified_context
 ssl.get_server_certificate
 tempfile.TemporaryDirectory.__init__
-types.UnionType  # Renamed from `types.Union`
 unicodedata.ucnhash_CAPI
 unittest.mock.create_autospec