Enable default services for all central use cases on BlueZ

Qt 5.9 introduced this behavior change as part of a bug fix. Qt 5.10
will force the new behavior unless otherwise requested by the user.

Task-number: QTBUG-61554
Change-Id: I75a2107c64e0eaaf03490658669c9a23ac7dcf63
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>