don't build llvm on aarch64.

Author: csyonghe

.github/workflows/ci.yml

@@ -56,7 +56,7 @@ jobs:
             platform: aarch64
             test-category: smoke
             full-gpu-tests: false
-            runs-on: ubuntu-24.04-arm
+            runs-on: ubuntu-22.04-arm
             has-gpu: false
           # Self-hosted full gpu build
           - os: windows
@@ -110,7 +110,7 @@ jobs:
           compiler: ${{matrix.compiler}}
           platform: ${{matrix.platform}}
           config: ${{matrix.config}}
-          build-llvm: ${{ matrix.platform != 'wasm' }}
+          build-llvm: ${{ matrix.platform != 'wasm' && matrix.platform != 'aarch64' }}
       - name: Build Slang
         if: steps.filter.outputs.should-run == 'true'
         run: |