[3.14] gh-142651: use `NonCallableMock._lock` for thread safety of `call_count` (GH-142922) (#145739)

gh-142651: use `NonCallableMock._lock` for thread safety of `call_count` (GH-142922)
(cherry picked from commit 728e4a075e3dae7e04edf90ad137a35073deb141)

Co-authored-by: Kumar Aditya <kumaraditya@python.org>