configuring default storage can results in charm error

[Adam Dyess]

Round on 1.27/edge build

reference of a key which doesn't exist in apply_default_storage

Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/__init__.py", line 74, in main
    bus.dispatch(restricted=restricted_mode)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 390, in dispatch
    _invoke(other_handlers)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 359, in _invoke
    handler.invoke()
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/.venv/lib/python3.10/site-packages/charms/reactive/bus.py", line 181, in invoke
    self._action(*args)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/charm/reactive/kubernetes_control_plane.py", line 1708, in configure_cdk_addons
    default_storage = configure_default_storage_class()
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/charm/reactive/kubernetes_control_plane.py", line 1675, in configure_default_storage_class
    apply_default_storage(storage_class, def_storage_class)
  File "/var/lib/juju/agents/unit-kubernetes-control-plane-0/charm/reactive/kubernetes_control_plane.py", line 1642, in apply_default_storage
    new_annotations = storage_class["metadata"]["annotations"].copy()
KeyError: 'annotations'

[Adam Dyess (addyess)]

PR: https://github.com/charmed-kubernetes/charm-kubernetes-control-plane/pull/281