[BUG] Entities requests broken on intents page

[IgorKrupenja]

Bug description:

1. Open https://admin.test.buerokratt.ee/training/training/intents.
2. Click on any intent in the list.
3. Open browser dev tools.

There are multiple /entities requests with 300 errors on Network tab.

This broke with b3c2ae1. Other pages are likely also affected.

Expected behavior:

/entities requests are successful everywhere.

[IgorKrupenja]

PR: #791

The PR also fixes issues with regexes requests on several pages.

Please test the following:

• https://admin.test.buerokratt.ee/training/training/intents - entities request
• http://admin.test.buerokratt.ee/training/training/regex/by_year - entities and regexes requests
• https://admin.test.buerokratt.ee/training/training/slots/currency - entities request
• http://admin.test.buerokratt.ee/training/training/stories/andmekaitse_k%C3%BCsimused - entities request

[ffrose]

Works as intended.