Auto merge of #11094 - y21:issue11084, r=Alexendoo

[`useless_vec`]: add more tests and don't lint inside of macros

Closes #11084.

I realized that the fix I added in #11081 itself also causes an error in a suggestion when inside of a macro. Example:
```rs
macro_rules! x {
  () => {
    for _ in vec![1, 2] {}
  }
}
x!();
```
Here it would suggest replacing `vec![1, 2]` with `[x!()]`, because that's what the source callsite is (reminder: it does this to get the correct span of `x!()` for code like `for _ in vec![x!()]`), but that's wrong when *inside* macros, so I decided to make it not lint if the whole loop construct is inside a macro to avoid this issue.

changelog: [`useless_vec`]: add more tests and don't lint inside of macros

r? `@Alexendoo` since these were your tests, I figured it makes most sense to assign you

clippy_lints/src/vec.rs

@@ -154,6 +154,10 @@ impl UselessVec {
         span: Span,
         suggest_slice: SuggestedType,
     ) {
+        if span.from_expansion() {
+            return;
+        }
+
         let mut applicability = Applicability::MachineApplicable;
 
         let snippet = match *vec_args {