add CLI flag disable-spans to toggle span trace logging

[obloomfield]

What does this PR do?

Adds a CLI flag, disable-spans (or environment variable DISABLE_SPANS) to remove the spans list and current span from the log trace when enabled. In production environments, the span's trace could contain sensitive user information, so this feature would be crucial for security compliance.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline,
  Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case. (Feature Request: add disable span CLI flag #483)
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines, and
  here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.

Follow-up Features

• (Feature Request: CLI Flag to filter user information out of logging trace #482) — Rather than removing spans, I made a larger feature request to add log filtering to remove user data from logging. This is likely the more desirable change, but requires a minor rewrite of the current logging system.

[Narsil]

LGTM

[Narsil]

Thanks for this.