update and pull back permissions in backend Dockerfile

[fergmac]

Describe the task
To resolve the permission issue associated with Django collect static command. Where the static files are copied over to "/app/staticfiles" we updated the permission inside the Dockerfile. We need to dial back the permissions to make this more secure.

Purpose
Improve security of the application. The current permission set is good for debugging.

Acceptance Criteria

• The backend container has the appropriate permissions to successfully and securely copy the static files over to the expected location

Additional context

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