Sets Storage Settings progress bar unselectable

Since it does nothing if users click it.

Bug: 184712147
Test: manual
Change-Id: I7d243ad465a5fa3f23297ac80c82bef4d078e34a
diff --git a/res/xml/storage_dashboard_fragment.xml b/res/xml/storage_dashboard_fragment.xml
index 9bca65a..adc29d3 100644
--- a/res/xml/storage_dashboard_fragment.xml
+++ b/res/xml/storage_dashboard_fragment.xml
@@ -27,6 +27,7 @@
     <com.android.settingslib.widget.UsageProgressBarPreference
         android:key="storage_summary"
         android:order="2"
+        android:selectable="false"
         settings:searchable="false"
         settings:controller="com.android.settings.deviceinfo.storage.StorageUsageProgressBarPreferenceController"
         settings:allowDividerBelow="true"/>