XWIKI-15848: A user cannot programatically unwatch the main wiki upon creation.

xwiki-platform-core/pom.xml

...ications/filters/NotificationFilterPreferenceManager.java

...cations/filters/NotificationFilterPreferenceProvider.java

.../internal/DefaultNotificationFilterPreferenceManager.java

...rnal/UserProfileNotificationFilterPreferenceProvider.java

...ions/filters/script/NotificationFiltersScriptService.java

...ernal/DefaultNotificationFilterPreferenceManagerTest.java

...filters/watch/internal/DefaultWatchedEntitiesManager.java

...ers/watch/internal/DefaultWatchedEntitiesManagerTest.java

...ers/watchlistbridge/internal/WatchlistBridgeProvider.java