[test] Fix Firefox browser version in karma profile config and resolve user-event test TODOs

[ZeeshanTamboli]

• I have followed (at least) the PR section of the contributing guide.

Typo spotted from #179 while working on mui/material-ui#42008.

Not certain if we've ever executed performance monitoring tests.

Additionally, I considered refactoring these TODOs:

• https://github.com/mui/material-ui/blob/next/packages/mui-base/src/MenuButton/MenuButton.test.tsx#L10-L12
• https://github.com/mui/material-ui/blob/next/packages/mui-base/src/Select/Select.test.tsx#L21-L23

now that we support the new Safari version, but I believe these components will undergo a refactor with a new API, so I left them as is.

[michaldudak]

Thanks!
As for the tests, we'd like to reuse as much as we can, so refactoring them will be useful anyway.

[ZeeshanTamboli]

Thanks! As for the tests, we'd like to reuse as much as we can, so refactoring them will be useful anyway.

Okay, I resolved the TODOs. Here's the browserstack-force run - https://app.circleci.com/pipelines/github/mui/base-ui/1317/workflows/61c67cfd-9b6f-408c-9fe0-60c6f99fad69/jobs/7582.