Remove run_on_exit decorator param

[hugorodgerbrown]

This is really only relevant for HttpResponse return values, and wrapping a view function with the decorator is no longer recommended. Extract logic into a separate function and wrap that instead.

BEFORE

# only process side-effects if the HttpResponse is 200 - ignore 404
@has_side_effects("foo", run_on_exit: lambda r: r.status_code=200)
def view_func(request: HttpRequest) -> HttpResponse:
    obj = get_obj_or_404()
    obj.foo()
    return HttpResponse("ok")

AFTER

def view_func(request: HttpRequest) -> HttpResponse:
    obj = get_obj_or_404()
    do_something_with_obj(obj)
    return HttpResponse("ok")

@has_side_effects("foo")
def do_something_with_obj(obj) -> None:
    obj.foo()