SurfaceFlinger: migrate capabilities to surfaceflinger.rc

SurfaceFlinger requires CAP_SYS_NICE which is set in
libcutils/fs_config.cpp. This is the old way of setting capabilities
and new the way is to set it directly on surfaceflnger.rc

Test: adb shell /data/nativetest64/SurfaceFlinger_test/SurfaceFlinger_test
Test: adb shell stop surfaceflinger && adb shell start surfaceflinger
Bug: 147271477
Change-Id: I680509a385928a9c929d4fe4857118af219e2b13