feat: Make Dockerfile compatible with OpenShift and non-root environments

[dotmobo]

This pull request refactors the Dockerfile to ensure compatibility with security-constrained container platforms like OpenShift, which enforce a "run as non-root" policy with an arbitrary user ID.

The previous Dockerfile was not suitable for these environments because it relied on:

1. The creation of a hardcoded ubuntu user (uid 1000).
2. A WORKDIR located in the user's home directory (/home/ubuntu).

This approach fails when the container is launched with an arbitrary, non-root user, as that user lacks permissions to write to the home directory or other root-owned locations.

To address this, the Dockerfile has been modified as follows:

• Removed User Creation: The USER instruction and useradd command have been removed. The container is now designed to be run by any user ID.
• Standardized WORKDIR: The working directory is now set to a neutral /app location.
• Permissions for Arbitrary Users: Added a RUN step using chgrp and chmod to adjust group ownership and permissions on the virtual environment's binaries (.venv/bin). This is the key
  change that allows an arbitrary user (belonging to the root group, GID 0) to execute the application.
• Cleaned up Paths: All paths and environment variables (like PATH and uv cache directories) have been updated to use the /app directory, ensuring all application-related files are kept
  in one place.

These changes make our container more secure and portable, enabling seamless deployment on OpenShift and other locked-down environments without sacrificing functionality.

[dotmobo]

It works fine on OpenShift, you just have to specify the HF cache folder with an env var in the helm chart like

  env:
    HF_HOME: "/cache/huggingface"

And mount a volume like :

volumeMounts:
            - name: speaches-cache
              mountPath: /cache/huggingface

Tested with faster whisper small and piper