Proxied requests to IMDS will never succeed since it's a link-local address
Updates the IMDS endpoint to include a trailing slash.
This is technically against the specification, but is successfully used by other AWS SDKs (such as Rust) to support kiam and other utilities which expect a trailing slash.
This PR:
Issue \
Closes https://github.com/awslabs/aws-sdk-kotlin/issues/1315 and closes https://github.com/awslabs/aws-sdk-kotlin/pull/1320
Description of changes
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