Fix wrong collection imports

bigbluebutton-html5/imports/api/users/server/modifiers/removeUser.js

 import { check } from 'meteor/check';
-import Users from '/imports/api/slides';
+import Users from '/imports/api/users';
 import Logger from '/imports/startup/server/logger';
 
 import setConnectionStatus from './setConnectionStatus';

bigbluebutton-html5/imports/api/users/server/modifiers/updateVoiceUser.js

 import { check } from 'meteor/check';
-import Users from '/imports/api/slides';
+import Users from '/imports/api/users';
 import Logger from '/imports/startup/server/logger';
 
 export default function updateVoiceUser(meetingId, userId, voiceUser) {