Exit gracefully from offscreen layer cycles

SurfaceFlinger would crash when encountering layer cycles,
and this path is primarily exercised when screenshotting an
offscreen layer root. Offscreen layers may have loops but are
not visited during display composition. However, screenshots
can be taken of offscreen layers. Catch the cycle and exit the
screenshot request as a no-op.

Fixes: b/382620055, b/432594483
Test: atest ScreenCaptureTest#captureOffscreenCyclicalHierarchyFails
Test: atest SurfaceFlinger_test
Test: atest CompositionTest
Flag: EXEMPT, bug fix
Change-Id: Ifb3efdadca0d4a28b312ab0b32b54b3941fa9c5d