Don't cache instance profile from IMDS credentials provider

[aajtodd]

Describe the bug

The profile attached to an EC2 instance can change during the lifetime of the instance. The current implementation caches the profile name and re-uses it on every request for credentials.

I have a use-case where the instance profile will change at some point during the execution, so getting credentials will stop working after that because the default credentials provider is requesting the credentials for the old profile.

Expected behavior

Profile name should be refreshed from IMDS unless explicitly overridden in code

Current behavior

Profile name is retrieved once and cached for the lifetime of the provider.

Steps to Reproduce

N/A

Possible Solution

No response

Context

This one stems from a bug filed against the Rust SDK, creating a mirrored issue here since we have the same behavior See https://github.com/awslabs/aws-sdk-rust/issues/384

AWS Kotlin SDK version used

0.9.5-beta

Platform (JVM/JS/Native)

JVM

Operating System and version

N/A