Allow network providers to set yield to bad wifi

While the "yield to bad wifi" policy is handled by CS for
backward compatibility, the network provider should in
fact be in control of it. There is no downside to allowing
providers to set it as no provider is using this, and it
will allow for migration in the future. The code is also
simpler, and becomes possible to test through CTS.

Test: NetworkScoreTest
Bug: 184037351
Change-Id: I3b2418f37bf1f0374d0a626fda7e2b6f3a3b41ba

services/core/java/com/android/server/connectivity/FullScore.java

@@ -108,9 +108,10 @@ public class FullScore {
     // and all bits managed by FullScore unset. As bits are handled from 0 up in NetworkScore and
     // from 63 down in FullScore, cut at the 32nd bit for simplicity, but change this if some day
     // there are more than 32 bits handled on either side.
-    // YIELD_TO_BAD_WIFI is temporarily handled by ConnectivityService.
-    private static final long EXTERNAL_POLICIES_MASK =
-            0x00000000FFFFFFFFL & ~(1L << POLICY_YIELD_TO_BAD_WIFI);
+    // YIELD_TO_BAD_WIFI is temporarily handled by ConnectivityService, but the factory is still
+    // allowed to set it, so that it's possible to transition from handling it in CS to handling
+    // it in the factory.
+    private static final long EXTERNAL_POLICIES_MASK = 0x00000000FFFFFFFFL;
 
     @VisibleForTesting
     static @NonNull String policyNameOf(final int policy) {