[3.13] gh-120289: Disallow disable() and clear() in external timer to prevent use-after-free (GH-120297) (#121984)

gh-120289: Disallow disable() and clear() in external timer to prevent use-after-free (GH-120297)
(cherry picked from commit 1ab17782832bb1b6baa915627aead3e3516a0894)

Co-authored-by: Tian Gao <gaogaotiantian@hotmail.com>