Use of GOTO_ON_BLINDXFR would not work at all.  The target location would
never be executed by the transferring channel.

* Made feature_blind_transfer() call ast_bridge_set_after_go_on() with
valid context, exten, and priority parameters from the transferring
channel.

* Renamed some feature_blind_transfer() local variables for clarity.

ASTERISK-25641 #close
Reported by Dmitry Melekhov

Change-Id: I19bead9ffdc4aee8d58c654ca05a198da1e4b7ac