Fix ConnectivityManagerTest#testFactoryReset flaky

Listen SoftAp callback to make sure soft ap is disabled
before start hotspot.

Bug: 277856014
Test: atest ConnectivityManagerTest#testFactoryReset

Change-Id: I95050be703b7c97da7a14541ac74718fdcbd7f13
diff --git a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
index ade89c0..5f4eb7c 100644
--- a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
+++ b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
@@ -2591,6 +2591,7 @@
             // prevent the race condition between airplane mode enabled and the followed
             // up wifi tethering enabled.
             tetherEventCallback.expectNoTetheringActive();
+            tetherUtils.expectSoftApDisabled();
 
             // start wifi tethering
             tetherUtils.startWifiTethering(tetherEventCallback);