Remove underscore from Jitsi conference names
Remove underscore from Jitsi conference names

Fixes https://github.com/vector-im/riot-web/issues/12929

Note: we don't need this to fix conferences in our hosted instance (riot.im or modular.im), but it is a common thing for self-hosters, including sometimes ourselves, to accidentally make mistakes on.
matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk