BioPortal performance and stability issues

[alexskr]

BioPortal has been sluggish and unstable for the last few weeks most likely due to an increased volume of bot traffic.
End users are seeing "queue is full" when accessing UI

Steps taken so far:

• adjust robots.txt via ncbo/bioportal_web_ui@8fcdded and ncbo/bioportal_web_ui@ea0bfbc
• increase PassengerMaxPoolSize from 30 to 100
• upgraded AllegroGraph from 8.0.1 -> 8.3.0 AllegroGraph: issues with long running queries. (Error: Stack overflow (signal 1000)) #331

[alexskr]

follow up:

• ActionController::UnknownFormat error from ChangeRequestsController bioportal_web_ui#361