Set exported flag to false.

It was set to true when the attribute became required in I878adb9108c95f06ddd059b23a542b61210edfa4

Bug: 222684510
Test: manual (see bug)
Change-Id: I8f67a5c3ac92f4813dc503cada8888833d7dbfbf
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index c84132f..cbb4e75 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -2236,7 +2236,7 @@
         </activity>
 
         <activity android:name=".password.ScreenLockSuggestionActivity"
-            android:exported="true"
+            android:exported="false"
             android:icon="@drawable/ic_suggestion_security">
             <intent-filter android:priority="1">
                 <action android:name="android.intent.action.MAIN" />