[MQ][Issue] Fix incorrect XML docs for public APIs

[scottaddie]

To learn more about the public API surface of a particular library, our customers often read the API ref docs published to learn.microsoft.com. Since the API ref docs are generated from XML docs (triple-slash comments) on public members within a library, it's imperative that we're writing valid XML docs for Track 2 libraries. The Learn platform's publishing pipeline assumes that XML docs are valid. One tool we can use to detect problems is @sharwell's unofficial Roslyn analyzers. Here are a couple Azure Monitor Query library PRs in which these analyzers were used:

• Fix blank list items in MetricsQueryClient API ref docs #43628
• Fix invalid XML docs in QueryTimeRange #43655