It is possible to not have the descriptor anymore by the time the
rendezvous circuit opens. Don't BUG() on that.
Instead, when sending the INTRODUCE1 cell, make sure the descriptor we
have (or have just fetched) matches what we setup in the rendezvous
circuit.
If not, the circuit is closed and another one is opened for a retry.
Fixes#40576
Signed-off-by: David Goulet <dgoulet@torproject.org>
