Reduce unnecessary reportResized of starting window

The starting window always fills its parent container. It won't show
different content depending on insets. So it can simply ignore.

Bug: 297502610
Test: Hot launch app.
      The trace won't contain "wm.reportResized_SnapshotStartingWindow".

Change-Id: I95bd33d80182f7a7c915d0d00ed075d14d6546cf