* Before this change, even on non-AWS platforms, the Enabled() check attempts
to make calls to the metadata endpoint when the session and credentials
are initialized (in order to determine if the provider should be
initialized at all).
* This can cause latency because the SDK times out and retries -- up to
20 seconds of latency has been observed on non-AWS platforms when the
metadata IP was blocked with an iptables rule.
* Instead, check once if we are running on an EC2 platform, first trying
to find the EC2 UUID in system files, and second attempting to get
credentials.
* Add a benchmark test that includes intialization and the credential
check.
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