Revert "Partially outline code inside the panic! macro".

Without any tests/benchmarks that show some improvement, it's hard to
know whether the change had any positive effect at all. (And if it did,
whether that effect is still achieved today.)

clippy_utils/src/macros.rs

@@ -250,18 +250,13 @@ impl<'a> PanicExpn<'a> {
         };
         let name = path.segments.last().unwrap().ident.name;
 
-        // This has no argument
-        if name == sym::panic_cold_explicit {
-            return Some(Self::Empty);
-        }
-
         let [arg, rest @ ..] = args else {
             return None;
         };
         let result = match name {
             sym::panic if arg.span.eq_ctxt(expr.span) => Self::Empty,
             sym::panic | sym::panic_str => Self::Str(arg),
-            sym::panic_display | sym::panic_cold_display => {
+            sym::panic_display => {
                 let ExprKind::AddrOf(_, _, e) = &arg.kind else {
                     return None;
                 };

clippy_utils/src/sym.rs

@@ -241,9 +241,6 @@ generate! {
     or_insert,
     or_insert_with,
     outer_expn,
-    panic_cold_display,
-    panic_cold_explicit,
-    panic_display,
     panic_str,
     parse,
     partition,