Ensuring setQsbSearchBar is called whenever the QSB is created

> On launcher3 when the QSB is created for the first time after a
widget drop, it is not set in searchDropTarget and as a result
the "Remove" and "App Info" drop targets are not visible until
Launcher3 restarts and rebinds QSB

Change-Id: I599a9a18cc5d46af790b3145dae2eb385b32b20e