Only create the packages-install-path / dbt_packages folder during dbt deps

[dbeatty10]

resolves #6985
resolves #9584

Problem

dbt commands other than dbt deps are making sure a directory exists at this configured packages-install-path (which defaults to "dbt_packages").

This is leading to the surprising behavior reported in #6985 and #9584.

Solution

Only create the packages-install-path / dbt_packages folder when running dbt deps.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc)
• This PR includes type annotations for new and modified functions

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.04%. Comparing base (c071868) to head (24d43d3).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9810      +/-   ##
==========================================
- Coverage   88.09%   88.04%   -0.05%     
==========================================
  Files         178      178              
  Lines       22461    22460       -1     
==========================================
- Hits        19787    19775      -12     
- Misses       2674     2685      +11     

Flag	Coverage Δ
integration	85.42% <ø> (-0.14%)	⬇️
unit	61.72% <ø> (-0.01%)	⬇️

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[QMalcolm]

Thank you for putting this together 🙂 It looks great!

Of note, part of #9584 is the following line

Rather, it should only create this directory when running dbt deps (and only if there is at least one package to install).

The in parentheses portion of that is to only create the directory when there are actually dependencies to install. I am absolutely okay with that not being part of this PR. However, we still want to implement that we can either create a new issue for just that part or I'm happy to pair and get that in as part of this PR.

[dbeatty10]

The in parentheses portion of that is to only create the directory when there are actually dependencies to install. I am absolutely okay with that not being part of this PR. However, we still want to implement that we can either create a new issue for just that part or I'm happy to pair and get that in as part of this PR.

I think the part in parentheses is already taken care of here in DepsTask whenever dbt deps is executed:

dbt-core/core/dbt/task/deps.py

Line 234 in 96f5426

system.make_directory(self.project.packages_install_path)

Just let me know if it looks like something key is missing!