Originally reported by @tonyghiani

Is your feature request related to a problem? Please describe.

We need to pass a percentage value to EuiFilterButton's numActiveFilters prop. It currently requires typecasting to any as the prop only accepts the number type.

Describe the solution you'd like

numActiveFilters prop should allow percentage values for these special cases. Extending the type to number | string with an appropriate JSDoc seems like a good solution.

Describe alternatives you've considered

• Casting the prop value to any works, but it's a bad practice.

Desired timeline

While a workaround is available, we'd like to have this as soon as possible so Kibana teams can use it.