feat(metrics): instrument ingester query response

Adds a QueryExec decorator that transparently injects instrumentation
into an Ingester query response stream.

This captures the wall-clock duration of time a query stream has taken
to be read to completion (or aborted) by the caller, faceted by
stream completed / dropped and batch error / all OK.

Also records the distribution of row, record batch, and partition count
per query to quantify the amount of data being read per query.

ingester2/src/query/mod.rs

@@ -9,6 +9,7 @@ pub(crate) mod response;
 
 // Instrumentation
 pub(crate) mod exec_instrumentation;
+pub(crate) mod result_instrumentation;
 pub(crate) mod tracing;
 
 #[cfg(test)]