Enable java bpf map always in U devices

Having SdkLevel.isAtLeastU() as a default value of
DeviceConfigUtils.isFeatureEnabled could result confusing behavior.
For example, when flag value is pushed to only the T device and the T
device with the flag is ugraded to U, this device could disable java bpf
map while the device keeps the flag value.
This CL prevents above confusing behavior.

Bug: 246218229
Test: atest BpfNetMaps
Change-Id: I615603c337bb94101dccac77ea0e6fa857041259
diff --git a/service/src/com/android/server/BpfNetMaps.java b/service/src/com/android/server/BpfNetMaps.java
index aea2103..b8a8fb4 100644
--- a/service/src/com/android/server/BpfNetMaps.java
+++ b/service/src/com/android/server/BpfNetMaps.java
@@ -281,7 +281,7 @@
         if (sEnableJavaBpfMap == null) {
             sEnableJavaBpfMap = DeviceConfigUtils.isFeatureEnabled(context,
                     DeviceConfig.NAMESPACE_TETHERING, BPF_NET_MAPS_ENABLE_JAVA_BPF_MAP,
-                    SdkLevel.isAtLeastU() /* defaultValue */);
+                    false /* defaultValue */) || SdkLevel.isAtLeastU();
         }
         Log.d(TAG, "BpfNetMaps is initialized with sEnableJavaBpfMap=" + sEnableJavaBpfMap);