Reorder RengineEngine and LayerSettings in VTS

VTS readback tests were crashing because RenderEngine before LayerSettings were deleted. LayerSettings holds onto ExternalTexture, which calls back into RenderEngine to clean up texture objects, so this was causing a UAF issue.

Bug: 372063484
Change-Id: Iad39e1a4aa9a9488af54742df121a981756b6275
Test: VtsHalGraphicsComposer3_TargetTest