Remove the @FlakyTest annotation from no longer flaky test

Change-Id: Ia0304a403981caf73022cbca9abb3b3dc212eb3c
Test: atest WMShellFlickerTest:ExitPipWithSwipeDownTest
Bug: none

libs/WindowManager/Shell/tests/flicker/src/com/android/wm/shell/flicker/pip/ExitPipWithSwipeDownTest.kt

@@ -16,7 +16,6 @@
 
 package com.android.wm.shell.flicker.pip
 
-import android.platform.test.annotations.FlakyTest
 import android.platform.test.annotations.Presubmit
 import android.view.Surface
 import androidx.test.filters.RequiresDevice
@@ -72,14 +71,6 @@ class ExitPipWithSwipeDownTest(testSpec: FlickerTestParameter) : ExitPipTransiti
             }
         }
 
-    @FlakyTest
-    @Test
-    override fun pipWindowBecomesInvisible() = super.pipWindowBecomesInvisible()
-
-    @FlakyTest
-    @Test
-    override fun pipLayerBecomesInvisible() = super.pipLayerBecomesInvisible()
-
     /**
      * Checks that the focus doesn't change between windows during the transition
      */