Rollup merge of #105523 - estebank:suggest-collect-vec, r=compiler-errors

Suggest `collect`ing into `Vec<_>`

Fix #105510.

Author: matthiaskrgr

core/src/iter/traits/iterator.rs

@@ -1829,6 +1829,7 @@ pub trait Iterator {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "iterator_collect_fn")]
     fn collect<B: FromIterator<Self::Item>>(self) -> B
     where
         Self: Sized,