Reduce slider handle size

[piitaya]

Proposed change

When migrating to material web component, the slider handle size was increased. This PR is a proposal to reduce the size because the UI can look too cluttered.

Before

After

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes Dot Slider #18417
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

[piitaya]

Checked with @matthiasdebaat. We will use 14px for the size.