res_pjsip_sdp_rtp.c: Use correct timeout when put on hold.

res_pjsip_sdp_rtp.c: Use correct timeout when put on hold.

When a call is put on hold and it has moh_passthrough and rtp_timeout
set on the endpoint, the wrong timeout will be used. rtp_timeout_hold is
expected to be used, but rtp_timeout is used instead. This change adds a
couple of checks for locally_held to determine if rtp_timeout_hold needs
to be used instead of rtp_timeout.

ASTERISK-30350

Change-Id: I7b106fc244332014216d12bba851cefe884cc25f