[llvm] [CI] Add --succinct to lit args (PR #152335)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> I don't know how well it works on GitHub but will be interested to see what you come up with.

It seems to end up as this:

```
2025-08-07T01:35:07.9676537Z Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90.. 
```

I don't remember seeing the progress indicated at all in the log while tests were running, but maybe I just missed it.

https://github.com/llvm/llvm-project/pull/152335