use emplace where appropriate per clang-tidy

The clang-tidy warning 'modernize-use-emplace' correctly flags a
few places where emplace should be used over push.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6ca79285a87d6927e718345dc8dce0387e6b1eda
diff --git a/redfish-core/lib/trigger.hpp b/redfish-core/lib/trigger.hpp
index cb27075..7bec478 100644
--- a/redfish-core/lib/trigger.hpp
+++ b/redfish-core/lib/trigger.hpp
@@ -107,7 +107,7 @@
         trigger["Severity"] = severity;
         trigger["DwellTime"] = *duration;
         trigger["Value"] = value;
-        triggers.push_back(std::move(trigger));
+        triggers.emplace_back(std::move(trigger));
     }
 
     return {std::move(triggers)};