Subgraph: Random text boxes appear in folded subgraph after switching back from Nodes 2.0

### Description

After switching from Nodes 2.0 mode back to the default rendering mode, text boxes that are contained within a subgraph randomly appear in the folded (but not minimized) subgraph view, even though they were not configured to be shown.

### Steps to Reproduce
1. Create a subgraph containing nodes with text box widgets
2. Switch to Nodes 2.0 mode
3. Switch back to the default (non-Nodes 2.0) mode
4. Observe that unconfigured text boxes now appear in the folded subgraph

### Expected Behavior
Only elements configured as "Shown on node" should appear in the folded subgraph view.

### Actual Behavior
Random text boxes that were not configured to be visible appear in the folded subgraph after switching back from Nodes 2.0.

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*Split from #9979*

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-10000-Subgraph-Random-text-boxes-appear-in-folded-subgraph-after-switching-back-from-Nodes-3256d73d3650817dba17f44ea49ae791) by [Unito](https://www.unito.io)

Reproduce the issue by creating a subgraph with text box widgets, switching to Nodes 2.0, and switching back to the default mode. Trace the folded subgraph rendering and the mode transition to determine why unconfigured text boxes become visible. Done means only elements configured as "Shown on node" appear after switching modes.

Written by the indexing model from the issue text.