SF: fix binder thread priority

Add setMinSchedulerPolicy to all binder interfaces SF exposes.
It was missing from gui::ISurfaceComposer and
gui::IDisplayEventConnection.

Test: presubmit
Bug: 299378819
Bug: 313924033
Change-Id: Ia0d99efa5a3bc58625c320d4df3c08bb597d2e38
Merged-In: Ia0d99efa5a3bc58625c320d4df3c08bb597d2e38
(cherry picked from commit 07d03c4d)