Revert a test change to make sure it's still testing the original issue

src/test/ui/pattern/issue-71042-opaquely-typed-constant-used-in-pattern.rs

@@ -4,7 +4,7 @@
 fn main() {
     const C: impl Copy = 0;
     match C {
-        C => {} //~ ERROR: `impl Copy` cannot be used in patterns
+        C | //~ ERROR: `impl Copy` cannot be used in patterns
         _ => {}
     }
 }

src/test/ui/pattern/issue-71042-opaquely-typed-constant-used-in-pattern.stderr

@@ -1,7 +1,7 @@
 error: `impl Copy` cannot be used in patterns
   --> $DIR/issue-71042-opaquely-typed-constant-used-in-pattern.rs:7:9
    |
-LL |         C => {}
+LL |         C |
    |         ^
 
 error: aborting due to previous error