Fix tests: explicitly set minzoom/maxzoom in test style geojson sources

Behaviour changed slightly in #919. Explicitly opt out by setting
min/maxzoom to keep old simplification behaviour, to keep pixel
identical test results.

Author: matzf

jvm/src/test/resources/styles/multisprite/style.json

@@ -7,6 +7,8 @@
   "name": "test-sprites",
   "sources": {
     "test_label": {
+      "minzoom": 0,
+      "maxzoom": 0,
       "type": "geojson",
       "data": {
         "type": "FeatureCollection",
@@ -371,4 +373,4 @@
     "duration": 0,
     "delay": 0
   }
-}
+}

jvm/src/test/resources/styles/style_geojson_ch_label.json

@@ -13,6 +13,8 @@
   "sources": {
 
     "test_label": {
+      "minzoom": 0,
+      "maxzoom": 0,
       "type": "geojson",
       "data": {
         "type": "FeatureCollection",