message: Only show key backup reminder when confirmed by server to be missing
  The key backup reminder was being shown too eagerly in cases when we hadn't
  actually checked with the homeserver on key backup status. This changes to only
  show the reminder when we're sure a backup doesn't exist.
  Fixes
diff: @@ -1768,7 +1768,7 @@ export default createReactClass({
  const showRoomRecoveryReminder = (
  SettingsStore.getValue("showRoomRecoveryReminder") &&
  this.context.isRoomEncrypted(this.state.room.roomId) &&
  - !this.context.getKeyBackupEnabled()
  + this.context.getKeyBackupEnabled() === false
  );
  const hiddenHighlightCount = this._getHiddenHighlightCount();
  