Remove torchtext from Build Official Docker images (pytorch#109799)

Fixes nightly official Docker image build.
Failures: https://hud.pytorch.org/hud/pytorch/pytorch/nightly/1?per_page=50&name_filter=Build%20Official

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### <samp>🤖 Generated by Copilot at 8671bfc</samp>

Remove `torchtext` installation from `Dockerfile` for arm64. This fixes the arm64 build of the PyTorch Docker image.

Pull Request resolved: pytorch#109799
Approved by: https://github.com/seemethere

Dockerfile

@@ -73,8 +73,8 @@ ARG TARGETPLATFORM
 
 # On arm64 we can only install wheel packages.
 RUN case ${TARGETPLATFORM} in \
-         "linux/arm64")  pip install --extra-index-url https://download.pytorch.org/whl/cpu/ torch torchvision torchaudio torchtext ;; \
-         *)              /opt/conda/bin/conda install -c "${INSTALL_CHANNEL}" -c "${CUDA_CHANNEL}" -y "python=${PYTHON_VERSION}" pytorch torchvision torchaudio torchtext "pytorch-cuda=$(echo $CUDA_VERSION | cut -d'.' -f 1-2)"  ;; \
+         "linux/arm64")  pip install --extra-index-url https://download.pytorch.org/whl/cpu/ torch torchvision torchaudio ;; \
+         *)              /opt/conda/bin/conda install -c "${INSTALL_CHANNEL}" -c "${CUDA_CHANNEL}" -y "python=${PYTHON_VERSION}" pytorch torchvision torchaudio "pytorch-cuda=$(echo $CUDA_VERSION | cut -d'.' -f 1-2)"  ;; \
     esac && \
     /opt/conda/bin/conda clean -ya
 RUN /opt/conda/bin/pip install torchelastic