stop installing manager header

Stop installing the manager header as it is no longer meant to be
exported, but rather used only internally within this repository.

Change-Id: I2ab21a31fd745e1b3e36fc39ffea5e26d373ff51
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/ipmi_commit_unittest.cpp b/test/ipmi_commit_unittest.cpp
index 30f78bf..85bd8f3 100644
--- a/test/ipmi_commit_unittest.cpp
+++ b/test/ipmi_commit_unittest.cpp
@@ -1,6 +1,6 @@
 #include "ipmi.hpp"
+#include "manager_mock.hpp"
 
-#include <blobs-ipmid/test/manager_mock.hpp>
 #include <cstring>
 
 #include <gtest/gtest.h>