res_sorcery_realtime: Fix leak of sorcery object type.

res_sorcery_realtime: Fix leak of sorcery object type.

This prevents a leak of a sorcery object type when realtime sorcery
objects are retrieved by fields or when multiple objects are retrieved.

The extent of this leak is that sorcery object types would be leaked.
These are allocated whenever an object type is registered with sorcery,
meaning that on module shutdown, these objects would be leaked. This
could be problematic if many reloads were performed, but it is not as
severe as if every sorcery object retrieved from realtime were being
leaked.

ASTERISK-25165 #close
Reported by Corey Farrell

Change-Id: I625c3b50eee4576670b7eeb013c81ad043b4b4f8