Make sure there are no ugly edge cases running Riot without an integrations manager

[manuroe]

From riot-web created by lampholder: element-hq/element-web#10090

Edge cases we need to manage (display an error or hide the feature):

• integration manager screen
• Sticker picker
• jitsi conf call

Fixed in Riot-web by matrix-org/matrix-react-sdk#3115

[manuroe]

Kamino cloned this issue to vector-im/riotX-android