[llvm] [update_test_checks] Generate multiple SAME lines to avoid back-reference issues. (PR #172452)

[Thomas Symalla via llvm-commits]

================
@@ -24,7 +24,7 @@
 2: --function-signature is now enabled by default and also checks return
    type/attributes.
 3: Opening parenthesis of function args is kept on the first LABEL line
-   in case arguments are split to a separate SAME line.
+   in case arguments are split to separate SAME lines.
----------------
tsymalla wrote:

If the generated check lines look like this:

```
define void @func(i32 [[group1:[[0-9]+]], ..., i32 [[group9:[[0-9]+]]), !md1 [[MD1:[0-9]+]], !md2 [[MD1]]
```  

We should run into this issue.

https://github.com/llvm/llvm-project/pull/172452