Check for Data Usage intent before populating "Data Usage" summary.

On some devices, data usage is not available; thus, it is possible that
ACTION_DATA_USAGE_SETTINGS has no matching activity. If no matching
activity is found, we should not populate "data usage" in the summary
field.

Bug: 111398942
Test: Manual check. I see that data usage is no longer visible on
devices without Data Usage activity.
Test: make RunSettingsRoboTests

Change-Id: I838206b76497c6550ef4826ad19e605cd32906ee