Merge pull request #12194 from apache/fix/graph-line-label

Fix/graph line label: keep the original distance between line label and line.

src/chart/graph/GraphSeries.js

@@ -242,7 +242,8 @@ var GraphSeries = echarts.extendSeriesModel({
         edgeSymbol: ['none', 'none'],
         edgeSymbolSize: 10,
         edgeLabel: {
-            position: 'middle'
+            position: 'middle',
+            distance: 5
         },
 
         draggable: false,