Remove cafile hack used for NPM 6

[markhallen]

What are you trying to accomplish?

Whilst working on adding the Bun package manager an issue was surfaced related to a custom cert used for NPM 6.

This PR removes the calfile from .npmrc.

See #11209

Anything you want to highlight for special attention from reviewers?

NPM 6 is no longer supported.

How will you know you've accomplished your goal?

No functional changes are observed.

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.