Only show the linear loading bar when reloading data.

We currently show the linear loading bar even when reloading the UI
without reloading data (e.g., when showing system apps).  This step
can take a non-trivial amount of time, during which the loading bar
isn't animated, so this looks janky.

Bug: 125332206
Test: Show/hide system apps, click refresh button.
Change-Id: I1f83082e932c971867651021d2062d98a9a8f57e