Remove valgrind junk, use CTest facilities instead

:Release Notes:
Rely on the stock CTest's 'make ExperimentalMemCheck' to check for
memory leaks.

:Detailed Notes:

:Testing Performed:
Built successfully, run memchecker.

:QA Notes:

:Issues Addressed:
[GF-6969] libpbnjson: Refactor jobject to use GHashTable instead of m_buckets

Open-webOS-DCO-1.0-Signed-off-by: Anatolii Sakhnik <anatolii.sakhnik@lge.com>

Change-Id: Ic1751cdf9b8f4de2cfdcd656caafab8d1a6b17cd
Reviewed-on: https://g2g.palm.com/2837
Reviewed-by: Build Verification
Reviewed-by: Anatolii Sakhnik <anatolii.sakhnik@lge.com>
Tested-by: Anatolii Sakhnik <anatolii.sakhnik@lge.com>
Reviewed-by: Alekseyev Oleksandr <alekseyev.oleksandr@lge.com>