Another fix for CI job refactoring (#9237)

Fixing #9227

matrix.timeout is not populated. Just hard-code the value now.

Also fix another cleanup DEMO_BACKEND_ID is not there anymore.

Test Plan: Make sure there are 6 jobs (test-models-linux) in the
pull.yml category.

Author: mergennachin

.github/workflows/pull.yml

@@ -56,7 +56,7 @@ jobs:
       docker-image: executorch-ubuntu-22.04-clang12
       submodules: 'true'
       ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
-      timeout: ${{ matrix.timeout }}
+      timeout: 90
       script: |
         # The generic Linux job chooses to use base env, not the one setup by the image
         CONDA_ENV=$(conda env list --json | jq -r ".envs | .[-1]")
@@ -65,11 +65,10 @@ jobs:
         MODEL_NAME=${{ matrix.model }}
         BUILD_TOOL=${{ matrix.build-tool }}
         BACKEND=${{ matrix.backend }}
-        DEMO_BACKEND_DELEGATION=${{ matrix.demo_backend_delegation }}
 
         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}" "${DEMO_BACKEND_DELEGATION}"
+        PYTHON_EXECUTABLE=python bash .ci/scripts/test_model.sh "${MODEL_NAME}" "${BUILD_TOOL}" "${BACKEND}"
 
   test-llama-runner-linux:
     name: test-llama-runner-linux