prop224 prepwork: Use of HS circuitmap in existing HS code.

The new HS circuitmap API replaces old public functions as follows:
   circuit_clear_rend_token -> hs_circuitmap_remove_circuit
   circuit_get_rendezvous -> hs_circuitmap_get_rend_circ
   circuit_get_intro_point -> hs_circuitmap_get_intro_circ_v2
   circuit_set_rendezvous_cookie -> hs_circuitmap_register_rend_circ
   circuit_set_intro_point_digest -> hs_circuitmap_register_intro_circ_v2

This commit also removes the old rendinfo code that is now unused.
It also fixes the broken rendinfo unittests.