EventIndex: Remove the unused deleteEventIndex method.
EventIndex: Remove the unused deleteEventIndex method.

We need to support the deletion of the event index even if it's not
currently initialized, therefore the deletion ended up in the
EventIndexPeg class.

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