[web] Fix wrong selector used to obtain connection

Summary:
issue: https://linear.app/comm/issue/ENG-4826/uncaught-typeerror-cannot-read-properties-of-undefined-reading-status
connection was moved to keyserverStore, so it should be fetched with connectionSelector. This was causing errors
useSelector from 'react-redux' was used instead the one from web/redux/redux-utils.js, so flow check did catch it before

Test Plan:
checked that the error disappeared
reloaded the page
logged out and back in
checked other places where we use useSelector from 'react-redux' on lib, web and native to see if I didn't miss anything else

Reviewers: michal, kamil, tomek

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D9047