Fulfill hanging promises upon LayerFE destruction

Attempted screenshots can have broken promises when there is an
invalid render area and no memory for the capture result. This
case would return without a capture result, but should also
clean up any promises associated with the LayerFEs in that
screenshot.

Fixes: b/330811287
Test: presubmit
Change-Id: I777aaff0096347332eb6ba731a8a74b4e1860a57