[ELE-830] Avoid writing to the Python package installation directory.

[elongl]

Is your feature request related to a problem? Please describe. Users often build a filesystem image that has the elementary-data Python package installed, and then mark their Python packages directory (site-packages) as read-only. This is problematic because at the moment running edr can do things that attempt to write to its installation directory. That is:

1. It runs dbt deps against the internal dbt project to download the Elementary dbt package.
2. It runs dbt which creates a target directory within the internal dbt project.
3. (Now solved) - It used to create logs/dbt.log but is now using edr_target instead.

Describe the solution you'd like For (1), have the dbt package already included within the Python package and remove the download logic. This will increase the Python package size so not entire sure that's the ideal solution. For (2), Do the same thing as with the dbt.log by defining DBT_TARGET_PATH here.

Additional context This would also solve the issue of https://github.com/elementary-data/elementary/issues/584.

_ELE-830