fix: broken main branch due to merge race in #21211

[zhuqi-lucas]

Which issue does this PR close?

Fixes compilation error and SLT test failure on main branch.

Rationale for this change

PR #21211 (Add output skewness metric) was based on a version before #21160 renamed MetricType::DEV to MetricType::Dev. When both merged, main broke with a compilation error. Additionally, #21211 changed the scan_efficiency_ratio display precision (e.g. 22% → 22.13%), causing one SLT test to fail.

What changes are included in this PR?

1. MetricType::DEV → MetricType::Dev in baseline.rs (compilation fix)
2. Update explain_analyze.slt expected output for scan_efficiency_ratio precision change

Are these changes safe?

Yes — fixes compilation error and test expectation, no behavior change.

[Copilot]

Pull request overview

Fixes a compilation break caused by using the stale MetricType::DEV enum variant after it was renamed to MetricType::Dev.

Changes:

• Update MetricType::DEV → MetricType::Dev for the derived output_rows_skew metric in baseline metrics.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[zhuqi-lucas]

CI status: cargo test, extended_tests, and build test all pass. The only failure is sqlite test suite which reports "query is expected to fail, but actually succeed" — this is a pre-existing issue on main (likely from #21126 fixing duplicate column name support), unrelated to this fix. That requires updating the datafusion-testing submodule's expected failure list.

[zhuqi-lucas]

Ok, it's duplicated with #21242