onnxruntime

[mobile] Fix for mac-ios-packaging pipeline (#22879)

### Description
Appends variant name to the Browserstack artifacts that are published so
that we don't run into the error:
"##[error]Artifact browserstack_test_artifacts already exists for build
609095."

[Working pipeline
run](https://aiinfra.visualstudio.com/Lotus/_build/results?buildId=609503&view=results)


### Motivation and Context
- onnxruntime-ios-packaging-pipeline has been failing