ServiceManagement: remove logspam

Remove happy path logspam.

Bug: 35355852
Test: hidl_test
Change-Id: I241bdb4212242c2e9d84079091d5219c22dd6d15
diff --git a/transport/ServiceManagement.cpp b/transport/ServiceManagement.cpp
index 9130d5b..958b9bd 100644
--- a/transport/ServiceManagement.cpp
+++ b/transport/ServiceManagement.cpp
@@ -116,8 +116,8 @@
                      << interfaceName << "/" << instanceName
                      << ": " << ret.description();
     }
-    LOG(INFO) << "Successfully registerReference for "
-              << interfaceName << "/" << instanceName;
+    LOG(VERBOSE) << "Successfully registerReference for "
+                 << interfaceName << "/" << instanceName;
 }
 
 struct PassthroughServiceManager : IServiceManager {