Move format_push_string and format_collect to pedantic (#13894)

Closes #11434 by moving `format_push_string` and `format_collect` to
pedantic.

changelog: Move `format_push_string` and `format_collect` to pedantic

clippy_lints/src/methods/mod.rs

@@ -3518,7 +3518,7 @@ declare_clippy_lint! {
     /// ```
     #[clippy::version = "1.73.0"]
     pub FORMAT_COLLECT,
-    perf,
+    pedantic,
     "`format!`ing every element in a collection, then collecting the strings into a new `String`"
 }