Remove catch clause on compat shim

registerSystemDefaultNetworkCallback no longer throws
UnsupportedApiLevelException as it has compatibility behavior down to Q,
so remove the catch clause for the checked exception.

The exception would previously not be thrown since the Tethering module
is only running on R+.

Bug: 182961265
Test: atest TetheringTests
Change-Id: I3c58235f3a59294995e5f32502fec6ccd17a3cf0
diff --git a/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
index 69471a1..5584db2 100644
--- a/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
+++ b/Tethering/src/com/android/networkstack/tethering/UpstreamNetworkMonitor.java
@@ -49,7 +49,6 @@
 import com.android.internal.util.StateMachine;
 import com.android.networkstack.apishim.ConnectivityManagerShimImpl;
 import com.android.networkstack.apishim.common.ConnectivityManagerShim;
-import com.android.networkstack.apishim.common.UnsupportedApiLevelException;
 
 import java.util.HashMap;
 import java.util.HashSet;
@@ -162,12 +161,7 @@
         }
         ConnectivityManagerShim mCmShim = ConnectivityManagerShimImpl.newInstance(mContext);
         mDefaultNetworkCallback = new UpstreamNetworkCallback(CALLBACK_DEFAULT_INTERNET);
-        try {
-            mCmShim.registerSystemDefaultNetworkCallback(mDefaultNetworkCallback, mHandler);
-        } catch (UnsupportedApiLevelException e) {
-            Log.wtf(TAG, "registerSystemDefaultNetworkCallback is not supported");
-            return;
-        }
+        mCmShim.registerSystemDefaultNetworkCallback(mDefaultNetworkCallback, mHandler);
         if (mEntitlementMgr == null) {
             mEntitlementMgr = entitle;
         }