Revert^2 "Second Patch for async RenderEngine"

Keep the change of Second Patch for async RenderEngine and fix the
regression

- remove the vector variables which is to store futureFence locally in
BufferStateLayer to get avoid fd leaking
- screenshots initiated from the app don't wait on the SF main thread.

2109270e

Bug: 202843200
Bug: 202833127
Bug: 202808760
Test: Wembley PIN setting test, NexusLauncherOutOfProcTests
Change-Id: I87847d01e2e330ddec88272cd8608f0b78c0a2cd