Update TAPL tests to dismiss all tasks safely

Flag: EXEMPT test refactor
Bug: 377678992
Test: pre/post-submit tests
Change-Id: I6a2225bea4f004bdc598e2c67ce26da9fd42f7a6

quickstep/tests/src/com/android/quickstep/TaplTestsKeyboardQuickSwitch.java

@@ -152,7 +152,7 @@ public class TaplTestsKeyboardQuickSwitch extends AbstractQuickStepTest {
 
     @Test
     public void testLaunchSingleRecentTask() {
-        mLauncher.getLaunchedAppState().switchToOverview().dismissAllTasks();
+        clearAllRecentTasks();
         startAppFast(CALCULATOR_APP_PACKAGE);
         mLauncher.goHome().showQuickSwitchView().launchFocusedAppTask(CALCULATOR_APP_PACKAGE);
     }

quickstep/tests/src/com/android/quickstep/TaplTestsOverviewDesktop.kt

@@ -35,10 +35,7 @@ import org.junit.Test
 class TaplTestsOverviewDesktop : AbstractQuickStepTest() {
     @Before
     fun setup() {
-        val overview = mLauncher.goHome().switchToOverview()
-        if (overview.hasTasks()) {
-            overview.dismissAllTasks()
-        }
+        clearAllRecentTasks()
         startTestAppsWithCheck()
         mLauncher.goHome()
     }

quickstep/tests/src/com/android/quickstep/TaplTestsQuickstep.java

@@ -548,7 +548,7 @@ public class TaplTestsQuickstep extends AbstractQuickStepTest {
     @EnableFlags(value = Flags.FLAG_ENABLE_GRID_ONLY_OVERVIEW)
     public void testDismissBottomRow() throws Exception {
         assumeTrue(mLauncher.isTablet());
-        mLauncher.goHome().switchToOverview().dismissAllTasks();
+        clearAllRecentTasks();
         startTestAppsWithCheck();
 
         Overview overview = mLauncher.goHome().switchToOverview();
@@ -570,7 +570,7 @@ public class TaplTestsQuickstep extends AbstractQuickStepTest {
     @EnableFlags(value = Flags.FLAG_ENABLE_GRID_ONLY_OVERVIEW)
     public void testDismissLastGridRow() throws Exception {
         assumeTrue(mLauncher.isTablet());
-        mLauncher.goHome().switchToOverview().dismissAllTasks();
+        clearAllRecentTasks();
         startTestAppsWithCheck();
         startTestActivity(3);
         startTestActivity(4);

tests/tapl/com/android/launcher3/tapl/BaseOverview.java

@@ -151,6 +151,10 @@ public class BaseOverview extends LauncherInstrumentation.VisibleContainer {
 
     /**
      * Dismissed all tasks by scrolling to Clear-all button and pressing it.
+     * <p>
+     * NOTE: Fails if there are already no recent tasks. If a test needs to start with an empty task
+     * list, check {@link #hasTasks} before calling this since the previous test may have already
+     * cleared the task list.
      */
     public void dismissAllTasks() {
         try (LauncherInstrumentation.Closable e = mLauncher.eventsCheck();