Separate volume ui and safety warning configs

VR headsets want to prevent 2d volume ui from being displayed, but want
to keep the high volume warning dialog.

Bug: 67951608
Bug: 68997348
Test: Tested linearly independent configs
Change-Id: Ic102ce626e199d2e3a3cf8fbb091050977c696bb
diff --git a/packages/SystemUI/res/values/config.xml b/packages/SystemUI/res/values/config.xml
index 5e7f9c6..e313e86 100644
--- a/packages/SystemUI/res/values/config.xml
+++ b/packages/SystemUI/res/values/config.xml
@@ -301,6 +301,9 @@
     <!-- Enable the default volume dialog -->
     <bool name="enable_volume_ui">true</bool>
 
+    <!-- Enable the default volume level warning dialog -->
+    <bool name="enable_safety_warning">true</bool>
+
     <!-- Whether to show operator name in the status bar -->
     <bool name="config_showOperatorNameInStatusBar">false</bool>