fix: make xqueue app dir traversable so automated jobs can source xqu…

[naincy128]

Problem

The xqueue/prod-edx-queued_submissions_to_cloudwatch Jenkins job started failing on the current prod xqueue instance:

/bin/sh: 1: .: cannot open /edx/app/xqueue/xqueue_env: Permission denied

The job SSHes in as xqueue_mgmt_commands and runs . /edx/app/xqueue/xqueue_env as that user. Only the following manage.py call goes through sudo -u www-data.

xqueue_env is already 0644 (see "setup the app env file"), so the file mode is not the problem. The parent directory is:

• /edx/app/xqueue is the xqueue user's home directory. The add_user role creates it with useradd, and no playbook sets a mode on it.
• On focal, useradd creates home directories as 0755. On jammy, HOME_MODE defaults to 0750, which gives drwxr-x--- xqueue:www-data.
• xqueue_mgmt_commands is not in www-data, so it cannot enter the directory to read the file.

This lines up with xqueue moving to jammy in #386.

Change

Add a task to the xqueue role that sets {{ xqueue_app_dir }} to 0755, so the directory is set up the same way on focal and jammy.