Add tests on graviton instances (#9207)

- **Create Arm64 Graviton instance docker image**
#9199
- **Test models on linux aarch64 graviton instances** 


In the next follow-up PR, I will trim macos jobs

Author: mergennachin

.github/workflows/trunk.yml

@@ -63,6 +63,37 @@ jobs:
         # Build and test executorch
         PYTHON_EXECUTABLE=python ${CONDA_RUN} bash .ci/scripts/test_model.sh "${MODEL_NAME}" "${BUILD_TOOL}" "${BACKEND}" "${DEMO_BACKEND_DELEGATION}"
 
+  test-models-linux-aarch64:
+    name: test-models-linux-aarch64
+    uses: pytorch/test-infra/.github/workflows/linux_job_v2.yml@main
+    permissions:
+      id-token: write
+      contents: read
+    strategy:
+      matrix:
+        model: [linear, add, add_mul, ic3, ic4, mv2, mv3, resnet18, resnet50, vit, w2l, mobilebert, emformer_join, emformer_transcribe]
+        backend: [portable, xnnpack-quantization-delegation]
+        runner: [linux.arm64.2xlarge]
+      fail-fast: false
+    with:
+      runner: ${{ matrix.runner }}
+      docker-image: executorch-ubuntu-22.04-gcc11-aarch64
+      submodules: 'true'
+      ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+      timeout: 90
+      script: |
+        # The generic Linux job chooses to use base env, not the one setup by the image
+        CONDA_ENV=$(conda env list --json | jq -r ".envs | .[-1]")
+        conda activate "${CONDA_ENV}"
+
+        MODEL_NAME=${{ matrix.model }}
+        BUILD_TOOL="cmake"
+        BACKEND=${{ matrix.backend }}
+
+        PYTHON_EXECUTABLE=python bash .ci/scripts/setup-linux.sh --build-tool "${BUILD_TOOL}"
+        # Build and test ExecuTorch
+        PYTHON_EXECUTABLE=python bash .ci/scripts/test_model.sh "${MODEL_NAME}" "${BUILD_TOOL}" "${BACKEND}"
+
   test-custom-ops-macos:
     name: test-custom-ops-macos
     uses: pytorch/test-infra/.github/workflows/macos_job.yml@main