Enable readability-container-size-empty tests

This one is a little trivial, but it does help in readability.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I5366d4eec8af2f781b3bad804131ae2eb806e3aa
diff --git a/redfish-core/lib/event_service.hpp b/redfish-core/lib/event_service.hpp
index 8c748f9..115bfee 100644
--- a/redfish-core/lib/event_service.hpp
+++ b/redfish-core/lib/event_service.hpp
@@ -232,7 +232,7 @@
 
                 if (regPrefixes && msgIds)
                 {
-                    if (regPrefixes->size() && msgIds->size())
+                    if (!regPrefixes->empty() && !msgIds->empty())
                     {
                         messages::mutualExclusiveProperties(
                             asyncResp->res, "RegistryPrefixes", "MessageIds");