Auto merge of #16387 - lnicola:metrics-sysroot, r=Veykril

internal: Fix sysroot metadata in metrics

CC https://github.com/rust-lang/rust-analyzer/pull/16380#issuecomment-1895550254

xtask/src/metrics.rs

@@ -117,6 +117,8 @@ impl Metrics {
             sh,
             "./target/release/rust-analyzer -q analysis-stats {path} --query-sysroot-metadata"
         )
+        // the sysroot uses `public-dependency`, so we make cargo think it's a nightly
+        .env("__CARGO_TEST_CHANNEL_OVERRIDE_DO_NOT_USE_THIS", "nightly")
         .read()?;
         for (metric, value, unit) in parse_metrics(&output) {
             self.report(&format!("analysis-stats/{name}/{metric}"), value, unit.into());