Allowlist jni libs of FrameworksNetsTests

This dir contains the following jni libs
- libnetworkstatsfactorytestjni
- libandroid_net_frameworktests_util_jni

Bug: 297405814
Test: b build $(bmod libnetworkstatsfactorytestjni) --config=android
Test: b build $(bmod libandroid_net_frameworktests_util_jni) --config=android

Change-Id: I3905396cab8df5ebbbf12eafcd9f96cde8305697