Fix a deprecated config string name for the storage manager settings.

The old string was used for configuration purposes, but the change was
removed. A previous patch accidentally used the old string for
choosing if the activity was exported or not.

Bug: 31621740

Change-Id: I9471e3a4c6d64d3fb8be7cbfcf058d35364892a5
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index f189627..e09a9d4 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -3004,7 +3004,7 @@
         </activity>
 
         <activity android:name="Settings$AutomaticStorageManagerSettingsActivity"
-                  android:exported="@bool/config_has_storage_manager"
+                  android:exported="@bool/config_storage_manager_settings_enabled"
                   android:label="@string/automatic_storage_manager_settings"
                   android:taskAffinity="">
             <intent-filter android:priority="1">