chore(magnification): wait sysui connection to control fullscreen magnification

For window magnification controlling we have a timeout to wait for
sysui connection ready. So for fullscreen magnification, we also adopt
this strategy to increase fullscreen magnification stabibility and
availibility when enabling border on sysui feature.

Bug: 337800504
Flag: NONE
Test: manually
      atest AccessibilityMagnificationTest
      atest MagnificationControllerTest
      atest FullScreenMagnificationControllerTest
      atest MagnificationConnectionManagerTest
Change-Id: I8e3fb26857d7b142f6c302ca3fe1f07f4ee4b197