Fix BUNDLER_CONFIG_ARGS variable mismatch in Dockerfile

[upsidedwn]

BUNDLER_CONFIG_ARGS was not being used by the bundle config command due to a typo. #18693

This PR is to this issue, however, previous version of Dockerfile used set clean 'true'. However, this no longer works with "newer" versions of Ruby gems (rubygems/rubygems#3271), which now requires a force option when cleaning system gems.

Since there is no way to set the force flag through config, a new ARG (BUNDLER_FORCE_CLEAN) is used to provide the option of whether to run bundle clean --force on system gems.

[github-actions]

Thanks for your pull request! We require for all contributed code to come from a from a unique branch in your repository before it can be merged.

Please create a new branch in your fork of framework and resubmit this from that branch.

If you are using Git on the command line that may look like:

# Checkout the master branch
git checkout master

# Create a new branch for your feature
git checkout -b <BRANCH_NAME>

# Add your new files
git add modules/my-cool-new-module

# Commit your changes with a relevant message
git commit

# Push your changes to GitHub
git push origin <BRANCH_NAME>

# Now browse to the following URL and create your pull request!
# - https://github.com/rapid7/metasploit-framework/pulls

This helps protect the process, ensure users are aware of commits on the branch being considered for merge, allows for a location for more commits to be offered without mingling with other contributor changes and allows contributors to make progress while a PR is still being reviewed.

Please do resubmit from a unique branch, we greatly value your contribution! 🎉

[smcintyre-r7]

Hey sorry it took so long to get to this. I looked through it and the code changes look sensible but we need a unique branch in order to merge it.