[RTF] wrong display of committees

[Elblinator]

if a user is added to several meetings and committees via the "add to meetings" option then only one of the new committees is displayed until a reload.

how to recreate:

1. create a new account A
2. go into account A and activate "add to meetings"
3. add at least two meetings from two different committees
4. go back to accout A
5. In the committees and meetings area only one committee is displayed
6. if the page is reloaded all committees will be displayed correctly

wanted behaviour:
the committees should be correctly displayed immediately

[bastianjoel]

When adding a user to multiple meetings of different committees with the user.assign_meetings action only one of the committees is added to the committee_ids of the user.