IN_MEMORY_DETACHED

this is almost the same as nm_settings_update2_flag_in_memory, with one difference: when later deleting the profile, the original profile will not be deleted.

Instead a nmmeta file is written to /run to indicate that the profile is gone. Note that if such a nmmeta tombstone file exists and hides a file in persistent storage, then when re-adding the profile with the same UUID, then the original storage is taken over again.