Eliminate proto_tree_add_text by formatting field hf_opcua_ByteString in a few places.

Change-Id: I9606aa36b7d7b6bb2ef2e7685e6629163ca83ef7
Reviewed-on: https://code.wireshark.org/review/5312
Reviewed-by: Michael Mann <mmann78@netscape.net>
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Evan Huus <eapache@gmail.com>