KCL: Skip serializing default values for AST nodes (#4193)

This will make our snapshots and JSON representations easier to read (making our tests less verbose).

src/lang/std/sketch.ts

@@ -1823,11 +1823,10 @@ export const updateStartProfileAtArgs: SketchLineHelper['updateArgs'] = ({
         start: 0,
         end: 0,
         body: [],
-        digest: null,
+
         nonCodeMeta: {
           start: [],
           nonCodeNodes: [],
-          digest: null,
         },
       },
       pathToNode,