Graphite: Changed range expansion from 1m to 1s (#19246)

Fixes #11472

public/app/plugins/datasource/graphite/datasource.ts

@@ -220,11 +220,11 @@ export class GraphiteDatasource {
     // exists for the specified range
     if (roundUp) {
       if (date.get('s')) {
-        date.add(1, 'm');
+        date.add(1, 's');
       }
     } else if (roundUp === false) {
       if (date.get('s')) {
-        date.subtract(1, 'm');
+        date.subtract(1, 's');
       }
     }