Fix ddtrace warnings at app start (#12941)

* Load HTTPClient before Datadog

The instrumentation needs it to be loaded before it can patch the
request methods.

* Don't split HTTPClient traces on domains yet

After the service explosion in Datadog APM last time, let's take a more
cautious approach.

* Turns out, we aren't even using the aws-sdk gems

This was added because we use Fog's AWS adapter, but Fog uses Excon
(which we're already instrumenting) instead of the AWS SDK directly.

app/lib/forem_stats_drivers/datadog_driver.rb

@@ -1,3 +1,5 @@
+require "httpclient"
+
 module ForemStatsDrivers
   class DatadogDriver
     include ActsAsForemStatsDriver
@@ -16,9 +18,8 @@ module ForemStatsDrivers
         c.use :http, split_by_domain: false
         c.use :faraday, split_by_domain: true
         c.use :excon, split_by_domain: true
-        c.use :httpclient, split_by_domain: true
+        c.use :httpclient, split_by_domain: false
         c.use :httprb, split_by_domain: true
-        c.use :aws
         c.use :rest_client
         c.use :concurrent_ruby
       end