fix(deploy): Correctly detect images in parent executions (#3203)

A previous refactor (#3011) reversed the order of stages returned from parent executions, which in turn caused a bug in the lookup of image id's.
If you have several image producing stages in a parent pipeline, for instance a "Find image by tag" stage followed by a bake stage, Spinnaker would now use the output of the "Find image by tag" stage instead of the bake stage. This PR changes it back to the former behaviour, so that the image closest to the current executing stage will be used.

orca-core/src/main/java/com/netflix/spinnaker/orca/pipeline/model/Stage.java

@@ -20,7 +20,10 @@
 import static java.lang.String.format;
 import static java.lang.String.join;
 import static java.nio.charset.StandardCharsets.UTF_8;
-import static java.util.Collections.*;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.emptyMap;
+import static java.util.Collections.emptySet;
+import static java.util.Collections.singletonList;
 import static java.util.stream.Collectors.toList;
 
 import com.fasterxml.jackson.annotation.JsonBackReference;
@@ -42,7 +45,17 @@
 import de.huxhorn.sulky.ulid.ULID;
 import java.io.IOException;
 import java.io.Serializable;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Base64;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
 import javax.annotation.Nonnull;
@@ -529,23 +542,25 @@ private static Stage findAncestor(Stage stage, Execution execution, Predicate<St
       if (parentPipelineStage.isPresent()) {
         matchingStage = findAncestor(parentPipelineStage.get(), parentPipelineExecution, predicate);
       } else {
-        List<Stage> parentPipelineStages = new ArrayList<>(parentPipelineExecution.getStages());
-        parentPipelineStages.sort(
-            (s1, s2) -> {
-              if ((s1.endTime == null) && (s2.endTime == null)) {
-                return 0;
-              }
-
-              if (s1.endTime == null) {
-                return 1;
-              }
-
-              if (s2.endTime == null) {
-                return -1;
-              }
-
-              return s1.endTime.compareTo(s2.endTime);
-            });
+        List<Stage> parentPipelineStages =
+            parentPipelineExecution.getStages().stream()
+                .sorted(
+                    (s1, s2) -> {
+                      if ((s1.endTime == null) && (s2.endTime == null)) {
+                        return 0;
+                      }
+
+                      if (s1.endTime == null) {
+                        return -1;
+                      }
+
+                      if (s2.endTime == null) {
+                        return 1;
+                      }
+
+                      return s2.endTime.compareTo(s1.endTime);
+                    })
+                .collect(toList());
 
         if (parentPipelineStages.size() > 0) {
           // The list is sorted in reverse order by endTime.