us-interstate icons with ref_length > 3

[nickpeihl]

The highway-shield-us-interstate layer looks for ref_length >= 6 and assigns the icon-image that translates to us_interstate_{ref_length}. But we don't have icons for us-interstate_4, us-interstate_5, and us-interstate_6.

https://github.com/openmaptiles/osm-bright-gl-style/blob/500e26e5be343eb60f82a63c77fa9f20082daec8/style.json#L2522-L2551

However, I don't expect there are any us-interstate networks with a ref_length > 3. So would it make sense to update this filter as such instead of creating new icons?

-"filter": ["all", ["<=", "ref_length", 6], 
+"filter": ["all", ["<=", "ref_length", 3], 
   ["==", "$type", "LineString"], 
   ["in", "network", "us-interstate"] 
 ]

[ZeLonewolf]

Interstate H201 in Hawaii is 4 digits.