cached-imds-client: cache static IMDS responses to avoid linklocal_allowance_exceeded on EC2

I recently encountered IMDS (Instance Metadata Service) request failures with this error: 1'caller': 'actor/actor.go:101', 2'error': 'operation error ec2imds: GetMetadata, failed to get rate limit token, retry quota exceeded, x available, y requested The root cause: the aws-sdk-go-v2 IMDS client exhausted its retry token bucket. The AWS SDK for Go v2 implements client-side rate limiting ("retry…