system_api: Remove D-Bus service constants for firewalld

Chrome is not supposed to call firewalld directly and use
permission_broker as intermediary. Since right now nobody seems
to be using firewalld on Chrome side, remove its service constants
so that nobody uses it in the future.

BUG=brillo:1240
TEST=trybots
CQ-DEPEND=CL:284975

Change-Id: If6a17b4be50dd54d1dd951f629b9ea88a61ccef1
Reviewed-on: https://chromium-review.googlesource.com/285025
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/dbus/service_constants.h b/dbus/service_constants.h
index 232d21c..420cbdd 100644
--- a/dbus/service_constants.h
+++ b/dbus/service_constants.h
@@ -2125,10 +2125,4 @@
 
 }  // namespace apmanager
 
-namespace firewalld {
-const char kFirewalldInterface[] = "org.chromium.Firewalld";
-const char kServicePath[] = "/org/chromium/Firewalld";
-const char kServiceName[] = "org.chromium.Firewalld";
-}  // namespace firewalld
-
 #endif  // DBUS_SERVICE_CONSTANTS_H_