🌍 Natural Earth earth features should have variable min_zoom

[nvkelso]

tl;dr

• Earth features still need variable min_zom
• Water layer features received variable min_zoom in v1.6

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@sensescape found this one in the Refill LOD sprint:

• https://github.com/tilezen/vector-datasource/blob/master/yaml/water.yaml#L102-L128

- filter: {featurecla: Lake}
    min_zoom: 0
    output: {kind: lake}
    table: ne

All these are seeing to min_zoom 0, but we should be sourcing from the scalerank (or future Natural Earth's min_zoom values directly in the future).

Check also earth values.

[nvkelso]

Earth:

• https://github.com/tilezen/vector-datasource/blob/master/yaml/earth.yaml#L55-L58

  - filter: {gid: true}
    min_zoom: 0
    output: {kind: earth}
    table: ne

[nvkelso]

The water layer portion of this was fixed in #1714 for v1.6 milestone.

The earth portion remains (it's hard coded at 0 min_zoom always now for Natural Earth).

[nvkelso]

Verified.