[llvm] [UTC] Don't leave dangling CHECK-SAME when removing CHECK lines (PR #82569)

[Alexander Richardson via llvm-commits]

================
@@ -235,6 +235,7 @@ def main():
             )
         else:
             # "Normal" mode.
+            skip_same_check_line = False
----------------
arichardson wrote:

```suggestion
            dropped_previous_line = False
```
I think this name makes it easier to understand.


https://github.com/llvm/llvm-project/pull/82569