Ensure sub-hierarchy screenshots inherit secure from parent.

If a sub-hierarchy is screenshot that doesn't include the parent layer
that had the secure flag, the screenshot request would not respect the
secure flag. This is incorrect because we want to ensure secure flag
remains on all children regardless of where in the hierarchy the
screenshot is taken.

Test: CaptureChildRespectsParentSecureFlag
Test: CaptureOffscreenChildRespectsParentSecureFlag
Test: LayerSnapshotTest#setSecureRootSnapshot
Bug: 308662081
Change-Id: I13f19a7fa4b9e51da0aa097314f015fe1340fc54