Remove obsolete chart view widgets.

ChartDataUsageView and ChartNetworkSeriesView are no longer being used.
Remove them to avoid the need to maintain obsolete codes.

Bug: 117433810
Test: rebuild and make RunSettingsRoboTests
Change-Id: I0c99725500926083bee693c102a323d563647c3a

color-check-baseline.xml

@@ -1501,22 +1501,6 @@
             column="9"/>
     </issue>
 
-    <issue
-        id="HardCodedColor"
-        severity="Error"
-        message="Avoid using hardcoded color"
-        category="Correctness"
-        priority="4"
-        summary="Using hardcoded color"
-        explanation="Hardcoded color values are bad because theme changes cannot be uniformly applied.Instead use the theme specific colors such as `?android:attr/textColorPrimary` in attributes.&#xA;This ensures that a theme change from a light to a dark theme can be uniformlyapplied across the app."
-        errorLine1="        settings:fillColorSecondary=&quot;#ff80cbc4&quot;"
-        errorLine2="        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
-        <location
-            file="res/layout/data_usage_chart.xml"
-            line="47"
-            column="9"/>
-    </issue>
-
     <issue
         id="HardCodedColor"
         severity="Error"