Fix: update default CSP policy to allow KB iframe. (#3714)
Fix: update default CSP policy to allow KB iframe. (#3714)

## What type of PR is this? (check all applicable)

- [x] Bug Fix

## Description

Without this change the Help Drawer couldn't load content anymore.

## Related Tickets & Documents

#3404
denisov-vlad/redash,alexanderlz/redash,denisov-vlad/redash,denisov-vlad/redash,getredash/redash,getredash/redash,alexanderlz/redash,alexanderlz/redash,getredash/redash,alexanderlz/redash,getredash/redash,getredash/redash,denisov-vlad/redash,denisov-vlad/redash