incidentd: fix memory leaks in a test

The static analyzer found many memory leaks in this file. Converting
everything to use unique_ptr became really ugly, and involved lots of
copying from lists of unique_ptr<Privacy> to lists of Privacy*. Since
these tests really don't seem to allocate much, freeing everything en
masse at the end should be good enough.

Bug: 27101951
Test: mma; memory leak warnings are gone. Running
/data/nativetest64/incidentd_test/incidentd_test shows no failures.
Change-Id: I151b7ef4e02ee736e4e833924c0500e8dbedcc49