ci: test: Use CI Docker image on Linux

This commit updates the CI workflow test job to use the Zephyr CI
Docker image (`docker-image`) on the Linux hosts mainly because many
PyPI packages do not provide the ARM64 Linux wheels and need to be
compiled during installation.

It also removes the environment setup steps that are no longer
necessary because the required components are already provided as part
of the CI Docker image.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

.github/workflows/ci.yml

@@ -287,7 +287,7 @@ jobs:
           MATRIX_TESTENVS+='{
               "name": "ubuntu-20.04-x86_64",
               "runner": "zephyr-runner-linux-x64-xlarge",
-              "container": "",
+              "container": "ghcr.io/zephyrproject-rtos/ci:master",
               "bundle-host": "linux-x86_64",
               "bundle-archive": "tar.xz"
             },'
@@ -297,7 +297,7 @@ jobs:
           MATRIX_TESTENVS+='{
               "name": "ubuntu-20.04-aarch64",
               "runner": "zephyr-runner-linux-arm64-xlarge",
-              "container": "",
+              "container": "ghcr.io/zephyrproject-rtos/ci:master",
               "bundle-host": "linux-aarch64",
               "bundle-archive": "tar.xz"
             },'
@@ -1238,6 +1238,7 @@ jobs:
 
     steps:
     - name: Set up Python
+      if: ${{ runner.os != 'Linux' }}
       uses: actions/setup-python@v4
       with:
         # Force Python 3.10 because the twister is not compatible with a Python
@@ -1252,24 +1253,9 @@ jobs:
         sudo rm -rf ${GITHUB_WORKSPACE}/*
         shopt -u dotglob
 
-        # Add CMake APT repository
-        wget https://apt.kitware.com/kitware-archive.sh
-        sudo bash kitware-archive.sh
-
         # Install required system packages
         sudo apt-get update
-        sudo apt-get install -y ccache cmake device-tree-compiler dos2unix \
-                                git gperf jq ninja-build wget
-
-        # Upgrade pip
-        python3 -m pip install --upgrade pip
-
-        # Install west
-        pip3 install --user --upgrade west
-        echo 'export PATH=~/.local/bin:"$PATH"' >> ~/.bashrc
-
-        # Install required Python packages
-        pip3 install --user --upgrade -r "${{ env.PYTHON_DEPS }}"
+        sudo apt-get install -y dos2unix jq
 
         # Set environment variables
         echo "TAR=tar" >> $GITHUB_ENV