packagers: yum: remove queryLocalCachePackages

The queryLocalCachePackages is a legacy from engine-upgrade, which is
actually not required as the interface of yum provides the showdups
query parameter to achieve the same.

Change-Id: Iaa1b0563aa45f44b157f65edc6237dbf4be940e8
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>