[llvm] [llvm] Remove `br i1 undef` from regression tests (PR #116161)

[Nuno Lopes via llvm-commits]

================
@@ -43,7 +41,7 @@ inner.latch:
   br i1 %cmp2, label %inner.header, label %exit
 
 outer.latch:
-  br i1 undef, label %outer.header, label %exit
+  br i1 %arg, label %outer.header, label %exit
----------------
nunoplopes wrote:

maybe replace this with false to keep the spirit of the original test

https://github.com/llvm/llvm-project/pull/116161