[NLL] Improve error spans for `regions-bounded-by-trait-requiring-static.rs` ui test

[marmeladema]

For test src/test/ui/regions/regions-bounded-by-trait-requiring-static.rs the error spans are not very precise when compared to non-nll mode.
This should be improved.

See comment posted by @jackh726 in #96212 (comment)

@rustbot label +A-NLL +NLL-diagnostics