Remove StatefulSetStartOrdinal feature gate to target stable in 1.31

pkg/apis/apps/types.go

@@ -236,9 +236,7 @@ type StatefulSetSpec struct {
 
 	// ordinals controls the numbering of replica indices in a StatefulSet. The
 	// default ordinals behavior assigns a "0" index to the first replica and
-	// increments the index by one for each additional replica requested. Using
-	// the ordinals field requires the StatefulSetStartOrdinal feature gate to be
-	// enabled, which is beta.
+	// increments the index by one for each additional replica requested.
 	// +optional
 	Ordinals *StatefulSetOrdinals
 }