refactor: [#1403] remove unused code

After discussing with @da2ce7 we don't think this is necessary.

Author: josecelano

packages/metrics/src/lib.rs

@@ -6,7 +6,6 @@ pub mod metric_collection;
 pub mod prometheus;
 pub mod sample;
 pub mod sample_collection;
-pub mod thread_safe_metric_collection;
 pub mod unit;
 
 #[cfg(test)]