Fix paths and tracks in transportation layer z12 and z13 (#1334)

This PR fixes a bug that causes that `track` lines disappear at z13. This bug was introduced in https://github.com/openmaptiles/openmaptiles/pull/1190, which adds rendering of paths and tracks at z12 and z13.

Before this PR:
z12: lines with `route_rank = 1` are added (no matter what `highway`).
z13: lines with `route_rank BETWEEN 1 AND 2` and `highway = 'path'` are added.
-> tracks with `route_rank=1` are added at z12 but not at z13.

After this PR
z12: lines with `route_rank = 1` and `highway IN ('path', 'track')` are added.
z13: lines with `route_rank BETWEEN 1 AND 2` and `highway IN ('path', 'track')` are added .
-> only tracks and paths are added at z12 and z13 (which was IMHO the goal of https://github.com/openmaptiles/openmaptiles/pull/1190)

* Add only the most important paths and tracks (route_rank=1) to z12 and more important ones (route_rank between 1-2 or sac_scale or has name) to z13.

layers/transportation/transportation.sql

@@ -376,12 +376,11 @@ FROM (
            AND
                CASE WHEN zoom_level = 12 THEN
                          CASE WHEN transportation_filter_z12(hl.highway, hl.construction) THEN TRUE
-                              WHEN n.route_rank = 1 THEN TRUE
+                              WHEN hl.highway IN ('track', 'path') THEN n.route_rank = 1
                          END
                     WHEN zoom_level = 13 THEN
                          CASE WHEN man_made='pier' THEN NOT ST_IsClosed(hl.geometry)
-                              WHEN hl.highway = 'path' THEN (
-                                                        hl.name <> ''
+                              WHEN hl.highway IN ('track', 'path') THEN (hl.name <> ''
                                                                    OR n.route_rank BETWEEN 1 AND 2
                                                                    OR hl.sac_scale <> ''
                                                                    )