Auto merge of #52767 - ljedrz:avoid_format, r=petrochenkov

Prefer to_string() to format!()

Simple benchmarks suggest in some cases it can be faster by even 37%:
```
test converting_f64_long  ... bench:         339 ns/iter (+/- 199)
test converting_f64_short ... bench:         136 ns/iter (+/- 34)
test converting_i32_long  ... bench:          87 ns/iter (+/- 16)
test converting_i32_short ... bench:          87 ns/iter (+/- 49)
test converting_str       ... bench:          54 ns/iter (+/- 15)
test formatting_f64_long  ... bench:         349 ns/iter (+/- 176)
test formatting_f64_short ... bench:         145 ns/iter (+/- 14)
test formatting_i32_long  ... bench:          98 ns/iter (+/- 14)
test formatting_i32_short ... bench:          93 ns/iter (+/- 15)
test formatting_str       ... bench:          86 ns/iter (+/- 23)
```

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstd/sys_common/wtf8.rs b/src/libstd/sys_common/wtf8.rs
index bbb5980bd9d..45204b56ead 100644
--- a/src/libstd/sys_common/wtf8.rs
+++ b/src/libstd/sys_common/wtf8.rs
@@ -1245,7 +1245,7 @@ mod tests {
     #[test]
     fn wtf8_display() {
         fn d(b: &[u8]) -> String {
-            format!("{}", &unsafe { Wtf8::from_bytes_unchecked(b) })
+            (&unsafe { Wtf8::from_bytes_unchecked(b) }).to_string()
         }
 
         assert_eq!("", d("".as_bytes()));