vec-shrink-panik: update expectations to work on LLVM 17

For some reason, the called function is `cleanup` on LLVM 17 instead of
`filter`.

r? @Amanieu

Author: durin42

tests/codegen/vec-shrink-panik.rs

@@ -25,7 +25,7 @@ pub fn issue71861(vec: Vec<u32>) -> Box<[u32]> {
 
     // Call to panic_cannot_unwind in case of double-panic is expected
     // on LLVM 16 and older, but other panics are not.
-    // CHECK: filter
+    // old-CHECK: filter
     // old-NEXT: ; call core::panicking::panic_cannot_unwind
     // old-NEXT: panic_cannot_unwind
 
@@ -40,7 +40,7 @@ pub fn issue75636<'a>(iter: &[&'a str]) -> Box<[&'a str]> {
 
     // Call to panic_cannot_unwind in case of double-panic is expected,
     // on LLVM 16 and older, but other panics are not.
-    // CHECK: filter
+    // old-CHECK: filter
     // old-NEXT: ; call core::panicking::panic_cannot_unwind
     // old-NEXT: panic_cannot_unwind