[Chip] variant default value

[LorenzHenk]

The Chip variant default value default does not follow the general api of standard.

• I have searched the issues of this repository and believe that this is not a duplicate.

Summary 💡

Many components use the variant value standard as default value (e.g. TextField, Tabs, Badge).

For some reason, the Chip component uses the value default instead (types, PropTypes).

I think this should be changed from default to standard or filled.

Fixing this would be a breaking change without much gain.

Is it worth the trouble?
Should this be normalized somewhere, so it's less likely to happen again?

Additional context

The PR, that introduced the variant prop: #12680

[oliviertassinari]

@mbrookes A v5 breaking change?

[eps1lon]

This is loosely related to #13028

I really like standard as opposed to the current tautology of 'default' being the default value.