Do not start `Timer` upon manual switching of internal process
Do not start `Timer` upon manual switching of internal process

Prevents `Timer` to prematurely start and timeout immediately if internal
processing is enabled manually with `Timer.set_process_internal(true)` or
`Timer.set_physics_process_internal(true)`.

Even if the internal processing is enabled manually, the user still has to
actually start the timer with `start()` method explicitly.

(cherry picked from commit afcb6f38db9c313328130b6632073cda7f3b98e0)

ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot