Replace the OTEL-based tracing layer with tracing based layers

crates/tower/src/lib.rs

@@ -0,0 +1,32 @@
+// Copyright 2023 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#![deny(clippy::all)]
+#![warn(clippy::pedantic)]
+#![allow(clippy::module_name_repetitions)]
+
+mod metrics;
+mod trace_context;
+mod tracing;
+mod utils;
+
+pub use self::{metrics::*, trace_context::*, tracing::*, utils::*};
+
+fn meter() -> opentelemetry::metrics::Meter {
+    opentelemetry::global::meter_with_version(
+        env!("CARGO_PKG_NAME"),
+        Some(env!("CARGO_PKG_VERSION")),
+        None,
+    )
+}