Further cleanup cfgs in the UI test suite

This commit does three things:
 1. replaces (the last remaining) never true cfgs by the FALSE cfg
 2. fix derive-helper-configured.rs (typo in directive)
 3. and comment some current unused #[cfg_attr] (missing revisions)

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs b/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs
index 6fe51330118..33fda822baa 100644
--- a/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs
+++ b/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs
@@ -1,7 +1,7 @@
 //@ compile-flags: --edition 2021
 
 pub fn demo() -> Option<i32> {
-    #[cfg(nope)]
+    #[cfg(FALSE)]
     {
         do yeet //~ ERROR `do yeet` expression is experimental
     }
@@ -9,7 +9,7 @@ pub fn demo() -> Option<i32> {
     Some(1)
 }
 
-#[cfg(nope)]
+#[cfg(FALSE)]
 pub fn alternative() -> Result<(), String> {
     do yeet "hello"; //~ ERROR `do yeet` expression is experimental
 }