core+daemon: eliminate scheduler::{schedule,cancel} wrappers

Also move core/global-io.hpp to daemon/global.hpp

Refs: #4528, #4883
Change-Id: I0b99029f1a19d7451aab57099cd3303b7eb42ff3
diff --git a/tests/daemon/mgmt/manager-common-fixture.cpp b/tests/daemon/mgmt/manager-common-fixture.cpp
index ee8d543..ed4344e 100644
--- a/tests/daemon/mgmt/manager-common-fixture.cpp
+++ b/tests/daemon/mgmt/manager-common-fixture.cpp
@@ -54,7 +54,7 @@
 }
 
 ManagerCommonFixture::ManagerCommonFixture()
-  : m_face(getGlobalIoService(), m_keyChain, {true, true})
+  : m_face(g_io, m_keyChain, {true, true})
   , m_dispatcher(m_face, m_keyChain, ndn::security::SigningInfo())
   , m_responses(m_face.sentData)
 {