Add default NetworkRecommendation to core.mk

This makes the apk avaiable on all devices and can be overridden on a
per-product basis using LOCAL_OVERRIDES_PACKAGES.

BUG: 33224286
Test: Verified with lunch aosp_bullhead-userdebug; make

Change-Id: Ib345193caa4431b6405294bd8759d93349335814
diff --git a/target/product/core.mk b/target/product/core.mk
index 0a4e0fd..10b2c9e 100644
--- a/target/product/core.mk
+++ b/target/product/core.mk
@@ -44,6 +44,7 @@
     Launcher2 \
     ManagedProvisioning \
     MtpDocumentsProvider \
+    NetworkRecommendation \
     PicoTts \
     PacProcessor \
     libpac \