Remove use of -isystem for googletest

Use standard include_dirs and a proxy header to manually suppress
warning. This solves the problem of sign conversion warning that
fire only when rolling into chrome.
Follow-up CLs will try to remove -isystem also to other
buildtools. Limiting the scope of this for now.

Change-Id: I8bc7924a95c7dd73cad54f447c122bd339e4e2a4
Bug: 129130827
diff --git a/test/cts/device_feature_test_cts.cc b/test/cts/device_feature_test_cts.cc
index eb57888..c91fe49 100644
--- a/test/cts/device_feature_test_cts.cc
+++ b/test/cts/device_feature_test_cts.cc
@@ -16,7 +16,7 @@
 
 #include <sys/sysinfo.h>
 
-#include <gtest/gtest.h>
+#include "test/gtest_and_gmock.h"
 
 namespace perfetto {