Small tweaks to entrypoint.sh to allow for non-interactive running

[audiodude]

Description

Please include:

• relevant motivation
  • Trying to run the docker image automatically (perhaps on Amazon ECR) and it requires these steps
• a summary of the change
  • Create the MODEL_DIR at the top of the script. This seems like an omission, I was not able to complete checkpoint download without this.
  • Pipe 'yes' to the conda clean command, so that interactive prompts are agreed to and no interaction is needed
• which issue is fixed.
  • N/A
• any additional dependencies that are required for this change.
  • N/A

Checklist:

• [ x ] I have changed the base branch to dev
• [ x ] I have performed a self-review of my own code
• [ x ] I have commented my code in hard-to-understand areas
• [ x ] I have made corresponding changes to the documentation