Fix dependency build for macOS

[alopezz]

What does this PR do?

• Removes references to DD_PYTHON_2 which is no longer defined at the job.
• Adds workflow file to cache key to prevent this kind of error from not being caught on the PR.
• Adds workflow files to triggers for pushes to master.

Motivation

#18577 breaks macOS builds as soon as there's a cache miss during builder setup: https://github.com/DataDog/integrations-core/actions/runs/10836797983/job/30071333931?pr=18212.

We missed this on #18577 because the cache key doesn't include the workflow key despite it potentially affecting the setup.

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Changelog entries must be created for modifications to shipped code
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[datadog-agent-integrations-bot]

The backport to 7.58.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-7.58.x 7.58.x
# Navigate to the new working tree
cd .worktrees/backport-7.58.x
# Create a new branch
git switch --create backport-18581-to-7.58.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 9eb8f2d97d7206f939ed09051022dc10bbd661cc
# Push it to GitHub
git push --set-upstream origin backport-18581-to-7.58.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-7.58.x

Then, create a pull request where the base branch is 7.58.x and the compare/head branch is backport-18581-to-7.58.x.