There already is the tfb_tcp_timer_stop_all method that is supposed to stop
all time events associated with a given tcpcb by given stack. Some time ago
it was doing actual callout_stop(). Today bbr/rack just mark their internal
state as inactive in their tfb_tcp_timer_stop_all methods, but tcpcb stays
in HPTS wheel and potentially called in from HPTS. Change the methods to
also call tcp_hpts_remove(). Note: I'm not sure if internal flag is still
relevant once we are out of HPTS wheel.
Call the method when connection goes to into TCP_CLOSED state, instead of
calling it later when tcpcb is freed. Also call it when we switch between
stacks.