fix: look for goals in steps rather than plans

small bugfix, we used to look for goals in plans, but they are part of
a plan.

ref: N25B-400

src/control_backend/agents/user_interrupt/user_interrupt_agent.py

@@ -336,7 +336,6 @@ class UserInterruptAgent(BaseAgent):
         else:
             self.logger.warning("Tried to send belief with unknown type")
             return
-
         belief = Belief(name=belief_name, arguments=None)
         self.logger.debug(f"Sending belief to BDI Core: {belief_name}")
         # Conditional norms are unachieved by removing the belief