tests: fix leak in ghostpad unit test
tests: fix leak in ghostpad unit test

The created pad is never used and overwritten with
another newly-created pad a few lines below.

surround-io/gstreamer,justinjoy/gstreamer,ensonic/gstreamer,collects/gstreamer,surround-io/gstreamer,surround-io/gstreamer,Lachann/gstreamer,Lachann/gstreamer,krieger-od/gstreamer,krieger-od/gstreamer,mparis/gstreamer,mparis/gstreamer,krieger-od/gstreamer,collects/gstreamer,jpxiong/gstreamer,lovebug356/gstreamer,cfoch/gstreamer,cfoch/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,mparis/gstreamer,krichter722/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,lovebug356/gstreamer,jpakkane/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,lubosz/gstreamer,cablelabs/gstreamer,ensonic/gstreamer,jpakkane/gstreamer,centricular/gstreamer,jpakkane/gstreamer,mparis/gstreamer,jpakkane/gstreamer,collects/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,mparis/gstreamer,surround-io/gstreamer,cfoch/gstreamer,jpxiong/gstreamer,centricular/gstreamer,cablelabs/gstreamer,lovebug356/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,cfoch/gstreamer,lubosz/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,shelsonjava/gstreamer,krieger-od/gstreamer,jpxiong/gstreamer,cablelabs/gstreamer,justinjoy/gstreamer,centricular/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,lubosz/gstreamer,collects/gstreamer,jpakkane/gstreamer,justinjoy/gstreamer,justinjoy/gstreamer,krichter722/gstreamer,krieger-od/gstreamer,cfoch/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,lubosz/gstreamer,jpxiong/gstreamer,lovebug356/gstreamer,collects/gstreamer,cablelabs/gstreamer,lovebug356/gstreamer,justinjoy/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,krichter722/gstreamer,cablelabs/gstreamer,lubosz/gstreamer,Lachann/gstreamer,ensonic/gstreamer