[PiP2] Make sure round corner is applied

Make sure round corner is applied in the following cases

- Screen rotation
- Fold and unfold
- Enter PiP from landscape to portrait, in button navigation mode

Fixed the missing round corner by calling syncPipSurfaceState for
unhandled transition in PipTransition#startAnimation

Flag: com.android.wm.shell.enable_pip2
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/fiwqaDEnoUGMrYlVunaGAn
Bug: 385152045
Test: Check the corner radius for the given CUJs, see also the video
Change-Id: I17ab0e97d27f2113347e12b8def4ffa0d9e5b228