Increase the maximum amount of possible retriggers to 9

[julienw]

As requested by @acreskeyMoz!

I tried using a native select so that you wouldn't have to open the select before selecting the value with the keyboard but I couldn't style it quickly properly, so I kept MUI's version for now.

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.42%. Comparing base (6020382) to head (06f96d6). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #760 +/- ## ======================================= Coverage 91.42% 91.42% ======================================= Files 87 87 Lines 2262 2263 +1 Branches 425 425 ======================================= + Hits 2068 2069 +1 Misses 171 171 Partials 23 23 ``` | [Flag](https://app.codecov.io/gh/mozilla/perfcompare/pull/760/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla) | Coverage Δ | | |---|---|---| | [](https://app.codecov.io/gh/mozilla/perfcompare/pull/760/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla) | `91.42% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mozilla#carryforward-flags-in-the-pull-request-comment) to find out more.

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[acreskeyMoz]

Thank you!