[llvm] [Instrumentation] Fix EdgeCounts vector size in SetBranchWeights (PR #99064)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

### Merge activity

* **Aug 26, 10:47 AM EDT**: @mtrofin started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/99064).


https://github.com/llvm/llvm-project/pull/99064