ethernet: remove buggy test expectations for compatibility

EthernetManagerTest#testCallbacks() should not enforce up/up/down/up
callbacks, so this bug can be fixed in mainline without breaking CTS13.

Test: atest EthernetManagerTest
Bug: 234314411
Change-Id: I1650bbc2a5883a874b92ecf2bcc7a56d01f4a905
Merged-In: I1650bbc2a5883a874b92ecf2bcc7a56d01f4a905