Fix comments on ResourceExhaustedScope enum values. (#855)

<!-- Describe what has changed in this PR -->
**What changed?**

Fixed comments on `RESOURCE_EXHAUSTED_SCOPE_NAMESPACE` and
`RESOURCE_EXHAUSTED_SCOPE_SYSTEM`. They were reversed.

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**Why?**

Because they were reversed.

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**Breaking changes**

Nope, comment only change.

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**Server PR**

n/a

Author: abenn135