Update the pytest logging options in example charm code

[tromai]

Charmcraft 4.4.0 has been released. This means charmcraft init will contain the new logging config added in canonical/charmcraft#2769.

We need to update the example charms at some point. I suggest we:

• Wait until docs: switch K8s tutorial charms to rock version of demo server #2649 lands and Charmcraft 4.4.0 available on Snap store stable.
• We also discovered an unexpected side effect of this config (see docs: remove log_cli and log_file ini options; keep them as cli arguments for integration tests #2654). I assume the fix for this issue will be a hotfix to Charmcraft, and doesn't need to go through the next release.

When we update the example charms, we can follow the final fix in #2654