refactor(client): clean up gatsby-node (#55640)

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

client/utils/gatsby/challenge-page-creator.js

@@ -146,6 +146,9 @@ exports.createChallengePages = function (createPage) {
   };
 };
 
+// TODO: figure out a cleaner way to get the last challenge in a block. Create
+// it during the curriculum build process and attach it to the first challenge?
+// That would remove the need to analyse allChallengeEdges.
 function getProjectPreviewConfig(challenge, allChallengeEdges) {
   const { block, challengeOrder, challengeType, usesMultifileEditor } =
     challenge;