BHV-14129: VideoTransportSlider: Does not unfreeze Spotlight upon dragfinish

### Issue:
VideoTransportSlider dragstart was freezing spotlight (indirectly via call to super class) but dragfinish was not unfreezing
### Fix:
add the unfreeze call to dragfinish

Enyo-DCO-1.1-Signed-off-by: Krishna Rangarajan <krishna.rangarajan@lge.com>