French regions and province boundary lines show too early

[nvkelso]

• What did you see? In France the region lines show at zoom 3, and the province lines at 5.5.
• What did you expect to see? I expect the region lines to show at zoom 6, and the province lines at zoom 8.

My expectations more closely match how the data is setup in Natural Earth in the min_zoom property. Instead the ETL here is using older scalerank values which aren't maintained in Natural Earth and have problems.

Generally we should be showing less features at early zooms, and overall.

See also:

• https://github.com/tilezen/vector-datasource/blob/master/yaml/boundaries.yaml#L17-L31

Instead we can probably do

• Straight lookup:
  • min_zoom: { col: min_zoom }
• Clamped lookup to avoid putting
  • min_zoom: { clamp: { max: 11, min: 3, value: { col: min_zoom } } }

New way (per zoom, not additive):

    - zoom 2 - 199 features
    - 3 @ 61
    - 4 @ 463 but they are all 4.6 and 4.7 so might be excluded to zoom 5
    - 5 @ 41
    - 6 @ 387 basic 
    - 6.6 @ 680
    - 6.7 @ 860
    - 7 @ 900
    -  7.7 @ 1024
    - 8 @ 1522
    - 8.7 @ 515
    - 9 and 10 and 11: 3,525 excluded since they are after OSM transition
    - zoom 2 to 7.7 @ 3,525 features

Old way:

    - [ 2,   2 ] @ 705 features
    - [ 3,   3 ] @ 636
    - [ 5,   4 ] @ 742
    - [ 5.5, 5 ] @ 1195
    - [ 6,   6 ] @ 1403
    - [ 6.7, 7 ] @ 1388
    - [ 6.8, 8 ] @ 1789
    - [ 7,   9 ] @ 1132
    -  [ 7,   0 ] @ 438
    - excluded: 750
    - zoom 2 to 7 @ 9,428 features

[nvkelso]

For tests:

• min bounds check of zoom 2 (nothing there)
• max bounds check of zoom 9 (nothing there)
• min_zoom not scalerank