Should not list an empty exclusion set in file filter dropdown.

[RaymondLim]

This one is similar to #7961, but is created manually in the preferences.

1. Debug > Open Preferences File.
2. Make an empty exclusion set by changing one of the file filters sets to have empty strings for name and patterns properties.
3. Save the preferences file.
4. Press Ctrl/Cmd+Shift+F to open the Find bar.
5. Click on File Filter dropdown button.

Result: You will see one empty entry in the dropdown list that will show edit and delete icons when you hover the entry.

[bchintx]

Merged PR fixed the issue for me. FBNC back to @RaymondLim