Don't show groups in share placeholder if group sharing is disabled

[tcitworld]

Steps to reproduce

1. Check out Dav respect disallow sharing with groups server#25658
2. Disallow sharing with groups in the sharing settings
3. Open the share section on a calendar

Expected behaviour

No mention of "groups" in the placeholder.

Actual behaviour

Mention of "groups" in the placeholder.

How to fix

• Fetch the config and inject it in the initialstate service in ViewController
• add the config into loadSettingsFromServer in Calendar.vue
• get the config from the store and condition the group showing in strings in CalendarListItemSharingSearch.vue
• add some tests for good mesure

[tcitworld]

Duplicate from #2744

[tcitworld]

Reopening since #2744 was closed