Increase preparation timeout (#4270)

* Increase preparation-timeout to 60 seconds

* Adapt `pvf_preparation_time` metric to the new value

node/core/pvf/src/metrics.rs

@@ -152,8 +152,21 @@ impl metrics::Metrics for Metrics {
 				prometheus::Histogram::with_opts(
 					prometheus::HistogramOpts::new(
 						"pvf_preparation_time",
-						"Time spent in preparing PVF artifacts",
+						"Time spent in preparing PVF artifacts in seconds",
 					)
+					.buckets(vec![
+						// This is synchronized with COMPILATION_TIMEOUT=60s constant found in
+						// src/prepare/worker.rs
+						0.1,
+						0.5,
+						1.0,
+						10.0,
+						20.0,
+						30.0,
+						40.0,
+						50.0,
+						60.0,
+					]),
 				)?,
 				registry,
 			)?,

node/core/pvf/src/prepare/worker.rs

@@ -35,7 +35,9 @@ use std::{sync::Arc, time::Duration};
 const NICENESS_BACKGROUND: i32 = 10;
 const NICENESS_FOREGROUND: i32 = 0;
 
-const COMPILATION_TIMEOUT: Duration = Duration::from_secs(10);
+/// The time period after which the preparation worker is considered unresponsive and will be killed.
+// NOTE: If you change this make sure to fix the buckets of `pvf_preparation_time` metric.
+const COMPILATION_TIMEOUT: Duration = Duration::from_secs(60);
 
 /// Spawns a new worker with the given program path that acts as the worker and the spawn timeout.
 ///