fix(dashboard): limit number of log lines that are fetched (#461)

[eysi09]

This is really just to prevent the browser from crashing on the user if the logs are huge. We still need better log support for the dashboard in general. E.g:

• Improve UI
• Fetch logs for individual services
• Merge new log entries with those already in the data sore

[edvald]

Looks good, but needs a breaking change block in the commit message, for the CLI parameter change.
Going forward, it would be good to separate the small UI tweaks from the things that affect the logs command etc. in commits.