Avoid send another copy splash screen request to shell.

Once the initial splash screen view transferred to client, core should
not request another copy request from shell since the SurfacePackage
was released in shell. Add a condition in transferSplashScreenIfNeeded
to ensure there won't request copy again.

Flag: EXEMPT bugfix
Bug: 370578484
Test: atest SplashscreenTests
Change-Id: I151befb077f196167044d1138605d5ecb4716021