MM-56929- Dont allow guests to be set via team API (#26286)

* dont allow guests to be set via team API

* comment out invalid test

* Update import_functions_test.go

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/team.go

@@ -484,12 +484,8 @@ func (a *App) UpdateTeamMemberSchemeRoles(c request.CTX, teamID string, userID s
 		return nil, model.NewAppError("UpdateTeamMemberSchemeRoles", "api.team.update_team_member_roles.guest.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	if isSchemeUser && isSchemeGuest {
-		return nil, model.NewAppError("UpdateTeamMemberSchemeRoles", "api.team.update_team_member_roles.guest_and_user.app_error", nil, "", http.StatusBadRequest)
-	}
-
-	if isSchemeAdmin && isSchemeGuest {
-		return nil, model.NewAppError("UpdateTeamMemberSchemeRoles", "api.team.update_team_member_roles.guest_and_admin.app_error", nil, "", http.StatusBadRequest)
+	if isSchemeGuest {
+		return nil, model.NewAppError("UpdateTeamMemberSchemeRoles", "api.team.update_team_member_roles.user_and_guest.app_error", nil, "", http.StatusBadRequest)
 	}
 
 	member.SchemeAdmin = isSchemeAdmin