Automatic merge from submit-queue (batch tested with PRs 57810, 57752). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Clarify error messages in HPA metrics
**What this PR does / why we need it**:
With the introduction of the RESTMetrics client, there are two ways to
fetch metrics for auto-scaling. However, they previously shared error
messages. This could be misleading. Make the error message more clearly
show which method is in use.
**Special notes for your reviewer**:
@DirectXMan12 re conversation in #56827
**Release note**:
```release-note
NONE
```
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