Sentry grouping broken because of "extra" logging

[marco-c]

Regression from #1333.

[La0]

We'll update the fingerprint to only report the msg part from structlog

[La0]

@EvaBardou suggested to update the papertrail formatting instead.

We need to support 2 things:

• reporting the full structlog output on papertrail
• using only the msg part for sentry fingerprint, still reporting the full data in the events data