b/418233958 Add new test case for Unlock the device back into Desktop Windowing to flicker test

Test: USE_RBE=false atest WMShellFlickerTestsDesktopMode:com.android.wm.shell.flicker.fundamentals.EnterDesktopFromLockScreenFlickerTest -c (http://ab/I68100010434334842)

Video: http://recall/-/fcs4X0Mzr4ubkwOgThJZ2l
Flag: EXEMPT add new test case
Bug: 418233958
Change-Id: I8926dccca0b4ba57f682e06323c59263e79c20a8