Rollup merge of #137807 - GuillaumeGomez:doctest-qualify-result, r=notriddle

Fully qualify `Result` in generated doctest code

As discussed in https://lore.kernel.org/rust-for-linux/20250228132553.880126-1-guillaume1.gomez@gmail.com/T/#u, it would require less code for RfL to be able to reach the same result (pun unintended).

cc ``@ojeda``

r? ``@notriddle``

Author: matthiaskrgr