Remove GroupBy.field_name from BanyanDB MeasureQuery request building

Author: currenjin

docs/en/changes/changes.md

@@ -6,6 +6,7 @@
 * Add Zipkin Virtual GenAI e2e test. Use `zipkin_json` exporter to avoid protobuf dependency conflict
   between `opentelemetry-exporter-zipkin-proto-http` (protobuf~=3.12) and `opentelemetry-proto` (protobuf>=5.0).
 * Fix missing `taskId` filter and incorrect `IN` clause parameter binding in `JDBCJFRDataQueryDAO` and `JDBCPprofDataQueryDAO`.
+* Remove deprecated `GroupBy.field_name` from BanyanDB `MeasureQuery` request building (Phase 1 of staged removal across repos).
 
 #### UI
 

oap-server/server-library/library-banyandb-client/src/main/java/org/apache/skywalking/library/banyandb/v1/client/MeasureQuery.java

@@ -182,7 +182,6 @@ BanyandbMeasure.QueryRequest build() throws BanyanDBException {
                     throw new IllegalArgumentException("field name cannot be null or empty if aggregation is specified");
                 }
             } else {
-                groupByBuilder.setFieldName(this.aggregation.fieldName);
                 BanyandbMeasure.QueryRequest.Aggregation aggr = BanyandbMeasure.QueryRequest.Aggregation.newBuilder()
                         .setFunction(this.aggregation.aggregationType.function)
                         .setFieldName(this.aggregation.fieldName)