Reorder release fence attachment for non-threaded RE

Changes when release fences are attached to layers for non-threaded
RenderEngine to ensure that fences are added and fired in the same
hop to the main thread. This removes the dependency on legacy screenshot
code and prevents a deadlock where screenshot requests are blocked on
the main thread while the main thread is blocked on the previous
screenshot request finishing.

Bug: b/351894825
Test: atest SurfaceFlinger_test
Flag: EXEMPT refactor and for flag removal
Change-Id: If9d4134aba1106484f94231c5104a57a605147b8