Filter empty value in ManifestPreview component

#708 (comment)

Signed-off-by: Sunghoon Kang <hoon@akuity.io>

ui/src/features/stage/manifest-preview.tsx

@@ -5,5 +5,14 @@ import { Stage } from '@ui/gen/v1alpha1/types_pb';
 import YamlEditor from '../common/code-editor/yaml-editor-lazy';
 
 export const ManifestPreview = ({ stage }: { stage: Stage }) => {
-  return <YamlEditor value={yaml.stringify(stage)} height='500px' disabled />;
+  const encodedStage = yaml.stringify(stage.toJson(), (_, v) => {
+    if (typeof v === 'string' && v === '') {
+      return;
+    }
+    if (Array.isArray(v) && v.length === 0) {
+      return;
+    }
+    return v;
+  });
+  return <YamlEditor value={encodedStage} height='500px' disabled />;
 };