🔥 Remove build_doc_test github action (#15680)

.github/workflows/build_doc_test.yml

-name: Documentation test build
-
-on:
-  pull_request:
-    paths:
-      - "src/**"
-      - "docs/**"
-      - ".github/**"
-
-jobs:
-  build_and_package:
-    runs-on: ubuntu-latest
-    defaults:
-      run:
-        shell: bash -l {0}
-
-    steps:
-      - uses: actions/checkout@v2
-      
-      - name: Loading cache.
-        uses: actions/cache@v2
-        id: cache
-        with:
-          path: ~/.cache/pip
-          key: v1-test_build_doc
-          restore-keys: |
-            v1-test_build_doc-${{ hashFiles('setup.py') }}
-            v1-test_build_doc
-
-      - name: Setup environment
-        run: |
-          pip install --upgrade pip
-          sudo apt-get -y update && sudo apt-get install -y libsndfile1-dev
-
-          pip install git+https://github.com/huggingface/doc-builder
-          pip install .[dev]
-
-          export TORCH_VERSION=$(python -c "from torch import version; print(version.__version__.split('+')[0])")
-          pip install torch-scatter -f https://data.pyg.org/whl/torch-${TORCH_VERSION}+cpu.html
-
-          pip install torchvision
-          python -m pip install 'git+https://github.com/facebookresearch/detectron2.git'
-
-          sudo apt install tesseract-ocr
-          pip install pytesseract
-          pip install pytorch-quantization --extra-index-url https://pypi.ngc.nvidia.com
-
-      - name: Make documentation
-        run: |
-          doc-builder build transformers ./docs/source