profiler-cli feedback after using it for bug 2062142

Now that profiling is enabled by default for mochitests, I attempted to use `fx-tests` and `profiler-cli` to burndown flakiness in a folder of mochitests ([Bug 2062142 - [meta] Fix the flakiness in browser/components/extensions/test/browser](https://bugzilla.mozilla.org/show_bug.cgi?id=2062142)). As part of my prompt, I asked to write down feedback for anything that got in the way with these tools. Here's a summary of the feedback that has been produced related to profiler-cli: [PROFILER_CLI_SUMMARY.md](https://github.com/user-attachments/files/31150465/PROFILER_CLI_SUMMARY.md)

I think some of these things are really worth fixing.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-1405)

Read PROFILER_CLI_SUMMARY.md first and use its listed profiler-cli feedback to identify which items are in scope. The issue does not name files, entry points, tests, or a specific acceptance criterion, so confirm the selected feedback and validation with maintainers before starting; done means the agreed items are fixed and verified.

Written by the indexing model from the issue text.