Some images don't build correctly with the rosidl_packages_interface

group depend. Make this dependent on an env variable which needs to
be set in order to pull that group in.

package.xml

@@ -59,7 +59,7 @@
   <test_depend>ros2run</test_depend>
   <test_depend>sensor_msgs</test_depend>
 
-  <group_depend>rosidl_interface_packages</group_depend>
+  <group_depend condition="$ROSIDL_INTERFACE_PACKAGES">rosidl_interface_packages</group_depend>
 
   <export>
     <build_type>ament_cmake</build_type>