Use themed font family for input forms to override materialize.css styling #18390

Description:

I noticed locally when running UI tests that materialize.css has some styles that set the font-family for text controls. This caused them to use the "Ubuntu" font locally, while everything styled by Matomo's CSS used "Liberation Sans" (from querying for sans-serif). Overriding that makes some UI tests pass locally for me now.

Review

• [ ] Functional review done
• [ ] Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• [ ] Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• [ ] Security review done
• [ ] Wording review done
• [ ] Code review done
• [ ] Tests were added if useful/possible
• [ ] Reviewed for breaking changes
• [ ] Developer changelog updated if needed
• [ ] Documentation added if needed
• [ ] Existing documentation updated if needed