Try to fix CI job for llm preset on macos (#11068)

### Summary
Use `-j` instead of `--parallel` fixes the timeout issue

### Test plan
See [`Build Presets / apple
(llm)`](https://github.com/pytorch/executorch/actions/runs/15192422780/job/42728334646?pr=11068)
passing

Author: larryliu0820

.github/workflows/build-presets.yml

@@ -27,12 +27,12 @@ jobs:
       runner: macos-latest-xlarge
       python-version: 3.12
       submodules: recursive
-      timeout: 90
+      timeout: 900
       script: |
         set -eux
         ${CONDA_RUN} ./install_requirements.sh > /dev/null
         ${CONDA_RUN} cmake --preset ${{ matrix.preset }}
-        ${CONDA_RUN} cmake --build cmake-out --parallel
+        ${CONDA_RUN} cmake --build cmake-out -j16
 
   linux:
     uses: pytorch/test-infra/.github/workflows/linux_job_v2.yml@main