LP#1974195: fix memory leak when performing fleshed Fieldmapper search

LP#1974195: fix memory leak when performing fleshed Fieldmapper search

This patch fixes a memory leak that occurs when performing
a fleshed search of an IDL class via open-ils.cstore, open-ils.pcrud,
or open-ils.rstore. It removes a debug-level log entry that didn't
free a temporary string.

To test
-------
[1] Perform a PCRUD search that includes fleshing and retrieves
    a large responses. One example is a search on bre that fleshes
    call numbers and copies and returns a few hundred bibs.
[2] Observe that the PCRUD drone that serviced the request has
    increased its memory usage significantly.
[3] Apply the patch and repeat step 1. This time, the drone's memory
    usage should not (persistently) increase as much.

Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>