Bluetooth: GATT: Fix not clearing CF_OUT_OF_SYNC

If the client is change-unware and disconnects the spec requires that
the stack still sends the error out of sync for the next request:

'The ATT_ERROR_RSP PDU is sent only once after the client becomes
change-unaware, unless the client _disconnects_ or the database changes
again before the client becomes change-aware in which case the
ATT_ERROR_RSP PDU shall be sent again'

Fixes #23110

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>