Fix an a11y issue that the the QAW activity announces "System UI"

instead of "Wallet" in talkback.

Root cause is that we set an empty title in WalletActivity, then the
application label wasn't override even if we set the activity label in
the AndroidManifest.

Test: manual
Bug: 198198195
Change-Id: I14f36f8e37664493b930dea18cfa0f6fc6021933

packages/SystemUI/src/com/android/systemui/wallet/ui/WalletActivity.java

@@ -116,7 +116,7 @@ public class WalletActivity extends LifecycleActivity implements
         if (toolbar != null) {
             setActionBar(toolbar);
         }
-        setTitle("");
+        getActionBar().setDisplayShowTitleEnabled(false);
         getActionBar().setDisplayHomeAsUpEnabled(true);
         getActionBar().setHomeAsUpIndicator(getHomeIndicatorDrawable());
         getActionBar().setHomeActionContentDescription(R.string.accessibility_desc_close);