fix(pipelinerun): add missing sort logic for childRefs array

The previous cherry-pick (tektoncd#9312) only included the test file changes
(removing cmpopts.SortSlices) but not the actual sorting logic in
pipelinerun.go. This caused tests to fail because they expected sorted
output but the production code wasn't sorting.

This commit adds the missing sort.Slice call that sorts childRefs by
PipelineTaskName, then Name, then Kind to prevent excessive status
updates caused by unordered arrays.

Cherry-pick of the missing part from tektoncd#9295.

Signed-off-by: Vincent Demeester <vdemeest@redhat.com>
Co-Authored-By: Claude <noreply@anthropic.com>

Author: vdemeester

pkg/reconciler/pipelinerun/pipelinerun.go

@@ -24,6 +24,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"regexp"
+	"sort"
 	"strings"
 	"time"
 
@@ -1748,6 +1749,18 @@ func updatePipelineRunStatusFromChildRefs(logger *zap.SugaredLogger, pr *v1.Pipe
 	for k := range childRefByName {
 		newChildRefs = append(newChildRefs, *childRefByName[k])
 	}
+
+	// sorting childRef in a specific order can greatly avoid
+	// meaningless updates of status caused by unordered arrays.
+	sort.Slice(newChildRefs, func(i, j int) bool {
+		if newChildRefs[i].PipelineTaskName == newChildRefs[j].PipelineTaskName {
+			if newChildRefs[i].Name == newChildRefs[j].Name {
+				return newChildRefs[i].Kind < newChildRefs[j].Kind
+			}
+			return newChildRefs[i].Name < newChildRefs[j].Name
+		}
+		return newChildRefs[i].PipelineTaskName < newChildRefs[j].PipelineTaskName
+	})
 	pr.Status.ChildReferences = newChildRefs
 }