tests(bundle-integration): Reduce idle_period to 30

Reduce idle_period from 120 to 30 to avoid huge amount of waiting and
tests failing. A very large idle_period had as a result the
wait_for_idle to time out due to one of the charms constantly doing
expected `execute` stuff in these two minutes.

tests/integration/test_kfp_functional.py

@@ -74,7 +74,7 @@ async def test_build_and_deploy(ops_test: OpsTest, request, lightkube_client):
         raise_on_blocked=False,  # These apps block while waiting for each other to deploy/relate
         raise_on_error=True,
         timeout=3600,
-        idle_period=120,
+        idle_period=30,
     )
 
 # ---- KFP API Server focused test cases