build: Deny clippy::absolute_paths

Removal of absolute paths is currently in progress. To avoid regressing
those changes add a clippy deny at the workspace level and at the crate
level override with #[expect(clippy::absolute_paths)]

See: #7670

Signed-off-by: Rob Bradford <rbradford@meta.com>

performance-metrics/src/main.rs

@@ -3,6 +3,9 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
+// TODO: Trim qualified paths in this crate, then drop this expectation.
+#![expect(clippy::absolute_paths)]
+
 // Custom harness to run performance tests
 mod micro_bench_block;
 mod performance_tests;