I've realized that what I'm looking for are finder plugins (I should have realized that sooner), even though the parent PID is launchd. I still can't figure out where finder plugins are stored.
Some of the process names are:
Seafile FinderSync Dropbox Finder Extension Box Sync Finder Extension
I'm going nuts trying to figure out how some processes are being automatically launched. The parent process is launchd (PID 1), but I can't find reference to them in any of the usual locations:
~/Library/LaunchAgents /System/Library/LaunchAgents /System/Library/LaunchDaemons /System/Library/StartupItems /Library/LaunchAgents /Library/LaunchDaemons /Library/StartupItems
I have also checked out cron:
/usr/lib/cron/tabs crontab -l sudo crontab -l
~/Library/Preferences/com.apple.loginitems.plist is empty.