use max border radius to show like a pill (microsoft#162360)

Author: sandy081

src/vs/workbench/browser/parts/activitybar/media/activityaction.css

@@ -184,7 +184,7 @@
 	justify-content: center;
 	align-items: center;
 	font-size: 14px;
-	border-radius: 8px;
+	border-radius: 10px;
 }
 
 /* Right aligned */