SF: Handle one-shot composition release fence

For instances like screenshots where there's going to be one shot
composition,there's not going to be a previous acquire fence nor a
present fence. This means that with the current implementation of
release fence merging, there's not going to be a release fence, which
would lead to immediate release.

This CL adds a special casing to detect when there's no fence from
merger of present fence and last client composition acquire fence. If
the merged fence is still a NO_FENCE, we try our best to return
something by using the current composition's acquire fence.

Bug: 435235974
Test: new libcompositionengine test case
Flag: com.android.graphics.surfaceflinger.flags.force_slower_follower_gpu_composition
Change-Id: I72a508e91e5ccdcd98e79dfd0be5489125345a42