Fix EthernetManagerTest

This patch fixes EthernetManagerTest as follows:
(1) testEnableDisableInterface_disableEnableEthernet
    Fix the test error when USB interface is present and treated as
    ethernet interfaces.
(2) testRemoveInterface_disableEnableEthernet
    Fix the error When tethering interface already presents.

Bug: 427055553
Test: atest ConnectivityCoverageTests
Flag: EXEMPT mainline

Change-Id: I2a31f3f0434b35e9ebe96b4f7003e5a9be0d3e81

tests/cts/net/src/android/net/cts/EthernetManagerTest.kt

@@ -843,6 +843,7 @@ class EthernetManagerTest {
 
     @Test
     fun testEnableDisableInterface_disableEnableEthernet() {
+        assumeFalse(restoreEthernetRule.isAdbOverEthernet())
         val iface = createInterface()
         val listener = TestInterfaceStateListener()
         addInterfaceStateListener(listener)
@@ -854,7 +855,6 @@ class EthernetManagerTest {
         listener.eventuallyExpectInterfaceStateChanged(iface.name, STATE_LINK_DOWN, ROLE_CLIENT)
         enableInterface(iface).expectError()
         disableInterface(iface).expectError()
-        listener.assertNoCallback()
 
         // When ethernet is enabled, enable/disableInterface() should succeed.
         restoreEthernetRule.setEthernetEnabled(true)
@@ -1006,6 +1006,8 @@ class EthernetManagerTest {
 
     @Test
     fun testRemoveInterface_disableEnableEthernet() {
+        assumeNoInterfaceForTetheringAvailable()
+
         // Set up 2 interfaces for testing
         val iface1 = createInterface()
         val listener = TestInterfaceStateListener()