Auto merge of #11442 - mitchhentges:87-debug-id, r=KiChjang

Fragment debug_id u16 only exists in debug, prod will format mem address

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Each fragment has a `u16` `debug_id` in debug mode, but no `debug_id` in production to save memory. To format a debug id in production, the address of the empty `debug_id` is displayed.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #87 (github issue number if applicable).

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- [X] These changes do not require tests because it looks like it's not possible to mock out `cfg` options in `#[test]`s

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