feat: process logs with >1 cookie section

[rgraber]

Description:

Update the process_cookie_monitoring_logs.py script to process log lines with multiple lists of cookie sizes. The difference doesn't turn out to be huge, mostly in total counts, but I think it's a simple enough fix that it's worth putting in so we get more complete data.

Issue:

https://github.com/edx/edx-arch-experiments/issues/151

Reviewers:

• [ ] tag reviewer

Merge checklist:

• [ ] All reviewers approved
• [ ] CI build is green
• [ ] Version bumped
• [ ] Changelog record added
• [ ] Documentation updated (not only docstrings)
• [ ] Commits are squashed

Post merge:

• [ ] Create a tag
• [ ] Check new version is pushed to PyPi after tag-triggered build is finished.
• [ ] Delete working branch (if not needed anymore)

Author concerns:

List any concerns about this PR - inelegant solutions, hacks, quick-and-dirty implementations, concerns about migrations, etc.