The displayer for the "List of users" property suggests disabled users

Important note:

Work left to do (follow-ups, out of scope of this issue):

• Other user displayers: the general-purpose user picker (uorgsuggest.vm + suggestUsersAndGroups.js) used outside XClass properties (e.g. rights, group membership, mentions) still suggests inactive users and has no equivalent option. It is a separate widget/code path and should be addressed in its own issue.
• Other display modes of the "List of Users" property: this PR only covers the picker/suggest path (REST class-property-values, DefaultUsersQueryBuilder). The non-picker display types (select/radio/checkbox, backed by UsersClass#getList()/getMap() via XWikiGroupService#getAllMatchedUsers) still list all users, including disabled ones. Making those consistent requires threading the filter through the group-service API and is left for a follow-up.