Iterate code snippet includes transformation code

### Type of issue

Other (describe below)

### Description

The code that shows how to iterate a syntax tree includes code that transforms the tree, which is described in the next paragraph.

For the sample, we should likely just duplicate the outer `foreach` loop so the snippet can be rendered correctly. Maybe even consider a `#if DEBUG` around it so it doesn't execute the loop twice when people download and try the sample.

### Page URL

https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/get-started/syntax-transformation

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/csharp/roslyn-sdk/get-started/syntax-transformation.md

### Document Version Independent Id

5f1f64a1-9d23-0010-b505-d3874041f8f2

### Article author

@BillWagner

### Metadata

* ID: 442d453e-38dd-ed79-741c-813429a41822
* Service: **dotnet-csharp**
* Sub-service: **roslyn-sdk**