fix(enriching): fix flush metrics for memory enrichment table

[esensar]

Summary

When flush_interval is not set for memory enrichment table (when data is flushed on every update) flush metrics are not properly updated. This changes that scenario to use the same flushing method, to ensure that object count, size and flush count metrics are properly updated.

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR. (Since memory enrichment table is not out yet)

Checklist

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    • cargo clippy --workspace --all-targets -- -D warnings
    • cargo nextest run --workspace (alternatively, you can run cargo test --all)
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References

Initial memory PR: #21348

[pront]

Thanks for the fix and adding more tests @esensar!

[pront]

Since this is an unreleased feature, we won't need a changelog for this PR.