Do not save bulletin settings in the notification settings

[Xfolchf]

Describe the bug
I try to activate the receipt of newsletters from the settings of my account (selecting the option and clicking "Save changes") and when I see the saved settings again, it is deactivated again.

https://meta.decidim.org/processes/bug-report/f/210/proposals/13339

Extra data (please complete the following information):

• Device: [e.g. iPhone6, Desktop]
• Device OS: [e.g. iOS8.1, Windows 10]
• Browser: [e.g. Chrome, Firefox, Safari]
• Decidim Version: [e.g. 0.10] 0.14
• Decidim installation: [e.g. MetaDecidim]

Additional context
Add any other context about the problem here.