ppp: change one test to legacy pppoe connection convention
A PPPoE connection can be defined in two ways:
-
by setting connection.interface-name to the base (Ethernet) interface. In this way, the name of the PPP interface will be determined automatically (in the form
pppX
); the base interface must be an Ethernet one, and no other connection can be active on it at the same time. Due to these shortcomings, this is considered the legacy way; -
since NM 1.10, one can set pppoe.parent to the name of the base interface, and connection.interface-name to the name of the PPP interface to be created. This is more flexible as it allows e.g. to run PPPoE over VLAN or Wi-Fi.
Currently all tests use the new way. Change one test to cover the legacy way, since it's still supported.