5-1/ Migrate CTS split screen testNonResizeable tests

1. testNonResizeableNotDocked
2. testNonResizeableWhenAlreadyInSplitScreenPrimary
3. testNonResizeableWhenAlreadyInSplitScreenSecondary
4. Refine the test flow to be more effeciency

Test: atest WMShellFlickerTests:EnterSplitScreenTest
Test: atest WMShellFlickerTests:AppPairsTest
Bug: 161435597

Change-Id: I271a522f220a65b1be7de6599a9ed185f06888b3