fix: set lease_ended in safety timeout test

The _should_run_after_lease_cleanup guard requires at least one
condition to be set. Set lease_ended since the test simulates a
scenario where cleanup is forced after timeout.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: raballew

python/packages/jumpstarter/jumpstarter/exporter/exporter_test.py

@@ -314,6 +314,7 @@ async def test_cleanup_forces_hook_set_on_safety_timeout(self):
         from unittest.mock import patch
 
         lease_ctx = make_lease_context()
+        lease_ctx.lease_ended.set()
         exporter = make_exporter(lease_ctx)
 
         statuses = []