[CodeQL] Change log messages that trigger CodeQL false-positives

CodeQL keeps thinking that the code below distributes sensitive information.

```
except KeyError:
logger.error(
"Non-existing field '%s' was attempted to be removed from the databag (relation ID: %s)",
str(field),
```

This is an issue for all Charm Developers who use `data-platform-libs`, as they ALL manually need to supress the error on their pipelines.