Do not delay updating WifiEntries for first onWifiEntriesUpdated()

The first callback of onWifiEntriesUpdated() after an onStart() should
update the list of WifiEntries without a delay. The callbacks afterwards
should remain delayed to show the progress bar.

Bug: 187473420
Test: build, visual inspection of entries being updated
Change-Id: Ie11ac156673b261157411e4d6216c454266b51a9