test: update cross-namespace diagnostic

[TorinAsakura]

Task

• Missing variables/fields give confusing error when name is the same as a built-in attribute like start or path rust#86290
• Blocked by Improve cross-namespace name diagnostics rust#159307

How to test

Before the fix

1. Context: Miri after Improve cross-namespace name diagnostics rust#159307 is included in rust-version
   Action: run tests/fail/rustc-error.rs
   Expected result: the old expectations do not match the rustc diagnostic

After the fix

1. Context: Miri after Improve cross-namespace name diagnostics rust#159307 is included in rust-version
   Action: run tests/fail/rustc-error.rs
   Expected result: the test accepts the new diagnostic, the note about the macro in another namespace, and the macro invocation suggestion

Proof

• Only tests/fail/rustc-error.rs and tests/fail/rustc-error.stderr are changed
• The targeted Miri run in the Rust PR passed: rust-lang/rust@61730f7
• Miri's current rust-version predates the Rust PR, so the local Miri UI run cannot exercise the new expectation yet

[oli-obk]

If there are rustc changes needed we land it in rustc together with those changes