Adding waiting for Launcher initialization

This may fix or ease TIS sometimes not receiving events.

Bug: 154157191
Change-Id: I5db9e88397788014dbba9716d777a2b97347828c

tests/src/com/android/launcher3/ui/AbstractLauncherUiTest.java

@@ -297,6 +297,7 @@ public abstract class AbstractLauncherUiTest {
             clearPackageData(mDevice.getLauncherPackageName());
             mLauncher.enableDebugTracing();
             mLauncherPid = mLauncher.getPid();
+            mLauncher.waitForLauncherInitialized();
         }
     }