Skip stopTetheringRequest tests if tethering isn't supported

Bug: 402315643
Test: atest TetheringManagerTest

Change-Id: I595ba20718cd13b7c6b6d66bf540c599ef48304e
diff --git a/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java b/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
index 7d6a213..abe628b 100644
--- a/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
+++ b/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
@@ -487,6 +487,9 @@
         final TestTetheringEventCallback tetherEventCallback =
                 mCtsTetheringUtils.registerTetheringEventCallback();
         try {
+            tetherEventCallback.assumeWifiTetheringSupported(mContext);
+            tetherEventCallback.expectNoTetheringActive();
+
             final StartTetheringCallback startTetheringCallback = new StartTetheringCallback();
             mTM.startTethering(new TetheringRequest.Builder(TETHERING_VIRTUAL).build(),
                     c -> c.run(), startTetheringCallback);
@@ -508,6 +511,7 @@
                 mCtsTetheringUtils.registerTetheringEventCallback();
         try {
             tetherEventCallback.assumeWifiTetheringSupported(mContext);
+            tetherEventCallback.expectNoTetheringActive();
 
             SoftApConfiguration softApConfig = new SoftApConfiguration.Builder()
                     .setWifiSsid(WifiSsid.fromBytes("This is one config"
@@ -532,6 +536,7 @@
                 mCtsTetheringUtils.registerTetheringEventCallback();
         try {
             tetherEventCallback.assumeWifiTetheringSupported(mContext);
+            tetherEventCallback.expectNoTetheringActive();
 
             SoftApConfiguration softApConfig = new SoftApConfiguration.Builder()
                     .setWifiSsid(WifiSsid.fromBytes("This is one config"