Add base.bootstrapped decorator to integration test

which allows to test to skip (instead of failing) if there's no
bootstrapped juju in the environment (which we don't in the merge jobs
in jenkins).

Looks like we accidentally took it out in
5b55b35#diff-9405e0bc34a26ab57891171003bb7253b44c20fa921670f44b207c1971b413f1

Author: cderici

tests/integration/test_model.py

@@ -341,6 +341,7 @@ async def test_deploy_from_ch_channel_revision_success(event_loop):
         await model.deploy("postgresql", application_name="test2", channel='latest/stable', revision=290)
 
 
+@base.bootstrapped
 @pytest.mark.asyncio
 async def test_deploy_trusted_bundle(event_loop):
     async with base.CleanModel() as model: