Removed flaky test from pre-submit

Bug: 159062106
Test: self
Change-Id: I780d8ac71651bb6da44aa54d694b8cb7c247bf1f
diff --git a/tests/framework/base/windowmanager/src/android/server/wm/PinnedStackTests.java b/tests/framework/base/windowmanager/src/android/server/wm/PinnedStackTests.java
index 2d8d3a2..042eb48 100644
--- a/tests/framework/base/windowmanager/src/android/server/wm/PinnedStackTests.java
+++ b/tests/framework/base/windowmanager/src/android/server/wm/PinnedStackTests.java
@@ -570,6 +570,7 @@
     }
 
     @Test
+    @FlakyTest(bugId=159062106)
     public void testDisallowMultipleTasksInPinnedStack() throws Exception {
         // Launch a test activity so that we have multiple fullscreen tasks
         launchActivity(TEST_ACTIVITY);