test: [skip e2e] fix race condition in TestQueryNodePipeline/TestBasic (#46218)

issue: #46217
The test was failing intermittently because it didn't wait for the
pipeline to finish processing messages before exiting. The test sent a
message to the pipeline and immediately returned, causing the deferred
Close() to execute before ProcessInsert, ProcessDelete, and UpdateTSafe
could be called.

Fix by:
- Moving message construction before mock expectations setup
- Adding a done channel to synchronize on UpdateTSafe completion
- Waiting for the signal before test exits

Signed-off-by: Wei Liu <wei.liu@zilliz.com>

internal/querynodev2/pipeline/pipeline_test.go

@@ -139,6 +139,15 @@ func (suite *PipelineTestSuite) TestBasic() {
 			}
 		})
 
+	// build input msg ahead of time to set up expectations
+	in := suite.buildMsgPack(schema)
+
+	// use a channel to signal when UpdateTSafe is called (last operation in pipeline)
+	done := make(chan struct{})
+	suite.delegator.EXPECT().UpdateTSafe(in.EndTs).Run(func(ts uint64) {
+		close(done)
+	}).Return()
+
 	// build pipleine
 	manager := &segments.Manager{
 		Collection: suite.collectionManager,
@@ -155,10 +164,11 @@ func (suite *PipelineTestSuite) TestBasic() {
 	suite.NoError(err)
 	defer pipelineObj.Close()
 
-	// build input msg
-	in := suite.buildMsgPack(schema)
-	suite.delegator.EXPECT().UpdateTSafe(in.EndTs).Return()
+	// send message to pipeline
 	suite.msgChan <- in
+
+	// wait for pipeline to process the message
+	<-done
 }
 
 func TestQueryNodePipeline(t *testing.T) {