[indvars] Missing variables at Og: (#69920)

https://bugs.llvm.org/show_bug.cgi?id=51735
https://github.com/llvm/llvm-project/issues/51077

In the given test case:
 ```
4 ...
 5 void bar() {
 6   int End = 777;
 7   int Index = 27;
 8   char Var = 1;
 9   for (; Index < End; ++Index)
10     ;
11   nop(Index);
12 }
13 ...
```
Missing local variable `Index` after loop `Induction Variable Elimination`. When adding a breakpoint at line `11`, LLDB does not have information on the variable. But it has info on `Var` and `End`.