clang-tidy: fix misc warnings

The following error reports have started to be reported by clang-tidy:

  * readability-qualified-auto - add 'const' to `auto&` iterators
  * bugprone-use-after-move - add break in loop after element is found

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I5314559f62f58aa032d4c74946b8e3e4ce6be808
diff --git a/redfish-core/lib/event_service.hpp b/redfish-core/lib/event_service.hpp
index 29175ab..9c5b378 100644
--- a/redfish-core/lib/event_service.hpp
+++ b/redfish-core/lib/event_service.hpp
@@ -573,7 +573,7 @@
             boost::beast::http::fields fields;
             for (const nlohmann::json& headerChunk : *headers)
             {
-                for (auto& it : headerChunk.items())
+                for (const auto& it : headerChunk.items())
                 {
                     const std::string* value =
                         it.value().get_ptr<const std::string*>();