* 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.
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