Filter list shows fields that are invisible to the currently logged in user

[jwalgran]

• Create a new instance
• Make "Tree Height" an invisible field for all roles
• Verify that "Tree Height" is one of the default mobile search fields.
• Choose the instance in the Android application and open the filter page

Expected: "Tree Height" is not an available filter
Actual: "Tree Height" is shown in the filter list

This was fixed in the iOS app in OpenTreeMap/otm-ios#280

NOTE: A different iOS bug appeared related to this fix OpenTreeMap/otm-ios#346. Make sure you take that into account.