Revert "fix: insertion marker's next blocks become real block (#7384)" (#7429)

This reverts commit 18ee0ec.

(cherry picked from commit 9db853d)

Author: rachel-fenichel

core/insertion_marker_manager.ts

@@ -225,12 +225,7 @@ export class InsertionMarkerManager {
     eventUtils.disable();
     let result: BlockSvg;
     try {
-      const blockJson = blocks.save(sourceBlock, {
-        addCoordinates: false,
-        addInputBlocks: false,
-        addNextBlocks: false,
-        doFullSerialization: false,
-      });
+      const blockJson = blocks.save(sourceBlock);
       if (!blockJson) {
         throw new Error('Failed to serialize source block.');
       }