Graphite: Fix splitting expressions in tag_value with template variables (#86958)

fix spilitting expressions in tag_value with template variables

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

@@ -511,7 +511,7 @@ export class GraphiteDatasource
 
     // special handling for tag_values(<tag>[,<expression>]*), this is used for template variables
     let allParams = interpolatedQuery.match(/^tag_values\((.*)\)$/);
-    let expressions = allParams ? allParams[1].split(',').filter((p) => !!p) : undefined;
+    let expressions = allParams ? allParams[1].split(/,(?![^{]*\})/).filter((p) => !!p) : undefined;
     if (expressions) {
       options.limit = 10000;
       return this.getTagValuesAutoComplete(expressions.slice(1), expressions[0], undefined, options);