OOIION-1374: fix calls to _get_recursion_parameter

So the recursion parameter is properly captured in the platform agent's FSM handlers.

Includes specific test exercising recursion=False with a small platform hierarchy: ion/services/sa/observatory/test/test_platform_launch.py:TestPlatformLaunch.test_hierarchy_recursion_false

@MauriceManning please review/merge.