Use postgis schema in database URL

This fixes an issue where the database adapter is not set correctly in
deployed environments as the schema in the URL is used to determine the
adapter. We need to use `postgis` so that we can use the features of
PostGIS.

Jira-Issue: 6706

Author: thomasleese

config/application.rb

@@ -41,7 +41,7 @@ class Application < Rails::Application
       dbname = db_config["dbname"]
       ENV[
         "DATABASE_URL"
-      ] = "postgres://#{username}:#{password}@#{host}:#{port}/#{dbname}"
+      ] = "postgis://#{username}:#{password}@#{host}:#{port}/#{dbname}"
     elsif ENV["DB_CREDENTIALS"].present?
       # for environment which uses RDS aurora managed credentials only the the username
       # and password is automatically set. The environment variable is then DB_CREDENTIALS
@@ -53,7 +53,7 @@ class Application < Rails::Application
       port = ENV.fetch("DB_PORT", 5432)
       ENV[
         "DATABASE_URL"
-      ] = "postgres://#{username}:#{password}@#{host}:#{port}/#{dbname}"
+      ] = "postgis://#{username}:#{password}@#{host}:#{port}/#{dbname}"
     end
 
     # Configuration for the application, engines, and railties goes here.