tests: refactor EthernetFixture

Also, use BOOST_TEST_INFO_SCOPE in a few places.

Change-Id: I113f326207825949ed9d3d22ade0654976d49b76
diff --git a/tests/daemon/mgmt/rib-manager-sl-announce.t.cpp b/tests/daemon/mgmt/rib-manager-sl-announce.t.cpp
index 6c82d4a..83a0af2 100644
--- a/tests/daemon/mgmt/rib-manager-sl-announce.t.cpp
+++ b/tests/daemon/mgmt/rib-manager-sl-announce.t.cpp
@@ -71,14 +71,14 @@
     loadDefaultPaConfig();
   }
 
-  template<typename ...T>
+  template<typename... T>
   ndn::PrefixAnnouncement
   makeTrustedAnn(T&&... args)
   {
     return signPrefixAnn(makePrefixAnn(std::forward<T>(args)...), m_keyChain, m_trustedSigner);
   }
 
-  template<typename ...T>
+  template<typename... T>
   ndn::PrefixAnnouncement
   makeUntrustedAnn(T&&... args)
   {