tests: Revert changes to s_normalUid/s_normalGid in MgmtGeneralConfigSection test suite

If changes to s_normalUid/s_normalGid are not reverted, the subsequent call
to PrivilegeHelper::drop() will throw exception if test cases run by an
unprivileged user.

Change-Id: I27e8b159d61e1b5f6dd21879f36ed63667f5c045
Refs: #2521
diff --git a/core/privilege-helper.hpp b/core/privilege-helper.hpp
index 6af2333..380dc64 100644
--- a/core/privilege-helper.hpp
+++ b/core/privilege-helper.hpp
@@ -71,7 +71,7 @@
   static void
   raise();
 
-private:
+PUBLIC_WITH_TESTS_ELSE_PRIVATE:
 #ifdef HAVE_PRIVILEGE_DROP_AND_ELEVATE
   static uid_t s_normalUid;
   static gid_t s_normalGid;