Instant Search: filter checkboxes should remain a consistent size

### Impacted plugin

Jetpack

### Steps to Reproduce

On a site with Instant Search enabled, set up a filter with long label names.

Perform a search on the front end of the site.

Check size of checkbox next to long label name, In comparison to the other check box sizes.

### A clear and concise description of what you expected to happen.

I would expect all checkboxes to be a consistent size.

### What actually happened

The text size on the label reduces to accomodate the length, and scales down the size of the corresponding checkbox with it.

### Other information


### Operating System

_No response_

### OS Version

_No response_

### Browser

Chrome/Chromium, Firefox, Safari

### Browser Version(s)

_No response_

Reproduce the issue in Jetpack Instant Search with a filter containing long labels, then locate the frontend filter and checkbox styling. Compare checkbox sizes across short and long labels; done means all checkboxes remain consistent while labels still accommodate long text, with coverage for the affected browsers.

Written by the indexing model from the issue text.