[llvm] [LTT] Add `unknown` branch weights when lowering type tests with conditional (PR #170752)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

* **#170752** <a href="https://app.graphite.com/github/pr/llvm/llvm-project/170752?utm_source=stack-comment-icon" target="_blank"><img src="https://static.graphite.dev/graphite-32x32-black.png" alt="Graphite" width="10px" height="10px"/></a> 👈 <a href="https://app.graphite.com/github/pr/llvm/llvm-project/170752?utm_source=stack-comment-view-in-graphite" target="_blank">(View in Graphite)</a>
* `main`


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https://github.com/llvm/llvm-project/pull/170752