treewide: Remove once_cell crate

`OnceCell` was added to the Rust standard library a while back, so it is
no longer necessary to use the 3rd party crate. This commit removes the
crate, replacing our only usage of `OnceCell` with `OnceLock`, which is
a thread-safe alternative.

Change-Id: Ifdb622c34c24ff40836276e25d2db8c33a2694df

Cargo.toml

@@ -153,7 +153,6 @@ nom_locate = "4.0.0"
 notify = "6.1.1"
 num-integer = "0.1.44"
 num_cpus = "1.16.0"
-once_cell = "1.14"
 opentelemetry = "0.21.0"
 opentelemetry-otlp = "0.14.0"
 opentelemetry-semantic-conventions = "0.13"

readyset-server/Cargo.toml

@@ -64,7 +64,6 @@ sha1 = { workspace = true }
 derive_more = { workspace = true }
 streaming-iterator = { workspace = true }
 proptest = { workspace = true }
-once_cell = { workspace = true }
 enum-kinds = { workspace = true }
 slotmap = { workspace = true }
 tikv-jemalloc-ctl = { workspace = true }

readyset-server/src/metrics/mod.rs

@@ -1,6 +1,7 @@
 //! Support for recording and exporting in-memory metrics using the [`metrics`] crate
 
-use once_cell::sync::OnceCell;
+use std::sync::OnceLock;
+
 use thiserror::Error;
 
 pub use crate::metrics::composite_recorder::{CompositeMetricsRecorder, RecorderType};
@@ -14,7 +15,7 @@ mod recorders;
 
 /// The type of the static, globally accessible metrics recorder.
 type GlobalRecorder = CompositeMetricsRecorder;
-static METRICS_RECORDER: OnceCell<&'static GlobalRecorder> = OnceCell::new();
+static METRICS_RECORDER: OnceLock<&'static GlobalRecorder> = OnceLock::new();
 
 /// Error value returned from [`install_global_recorder`] if a metrics recorder is already set.
 ///

readyset-tracing/Cargo.toml

@@ -7,7 +7,6 @@ edition = "2021"
 
 [dependencies]
 clap = { workspace = true, features = ["derive","env"] }
-once_cell = { workspace = true }
 parking_lot = { workspace = true }
 rand = { workspace = true }
 serde = { workspace = true, features = ["derive"] }