Remove broken openstreetmap URL

Temporary "fix" because the validity of the SSL cert of openstreetmap.de has
expired.

main.json

@@ -213,12 +213,6 @@
          "id":16,
          "name":"website_openstreetmap",
          "opacity":1,
-         "properties":[
-                {
-                 "name":"openWebsite",
-                 "type":"string",
-                 "value":"https:\/\/www.openstreetmap.de\/karte.html?zoom=19&lat=51.33637&lon=12.33817&layers=B000"
-                }],
          "type":"tilelayer",
          "visible":true,
          "width":100,
@@ -3488,4 +3482,4 @@
  "type":"map",
  "version":1.4,
  "width":100
-}
+}