Clean up and fix outdated references in resources.

[vallivaara]

There were some outdated non-existent resources in the resource XML:s, addressed by this confused developer. Removed and updated those just to avoid this kind of confusion in the future.

• https://indooratlas.freshdesk.com/a/tickets/3097
• Completely removed activity_resources.xml, as I (and my IDE) could not find any usages for it
• Everything seems to be working as before, as expected