Improve log messages `500 - {JSON blob}`

[nickvergessen]

There are various bad messages (mostly warnings) in the log that leave the admin with no clue if they need to do something:

# I guess no?
"500 - {\"status\":-1,\"exception\":\"OCA\\\\Social\\\\Exceptions\\\\ActorDoesNotExistException\",\"message\":\"Actor not found\"}"
# This is a bug?
"500 - {\"status\":-1,\"exception\":\"OCA\\\\Social\\\\Exceptions\\\\UnauthorizedFediverseException\",\"message\":\"Empty Origin\"}"
# I guess no?
"500 - {\"status\":-1,\"exception\":\"OCA\\\\Social\\\\Tools\\\\Exceptions\\\\RequestNetworkException\",\"message\":\"28 - Resolving timed out after 10000 milliseconds …