User Experience: Not seeing pie charts when selecting 1 event type

[GuillaumeZhang321]

Bug Description:

In statistics view, user gets shown no data when selecting a single event type.

Instead of showing nothing, we can enhance the user experience by still showing the global pie chart.

Steps to Reproduce:

1. Open a trace with more than two event types
2. Select a window of traces that contains only one event type.
3. "No Data" is shown instead of any pie charts

Fix

In org.eclipse.tracecompass.internal.tmf.ui.viewers.piecharts.TmfPieChartViewer.refresh, instead of making an empty viewer when less than two events types are selected, show the change shows the global pie chart.

Additional Information

• Operating System: Windows 11
• Trace Compass Version: 11.3