Standardize aggregation defaults and labels across metrics, spans, and logs

## Summary

Aggregation rate labeling and defaults are inconsistent across metrics, spans, and logs. Currently, per-second is the default rate unit, but per-minute is a more intuitive threshold for most users. All three data types should follow a single, consistent pattern for how aggregation queries are named and displayed.

## Background

Metrics tooltips currently default to showing rates as `per_second`. For the majority of use cases, per-minute is easier to reason about and better aligned with common monitoring conventions. Spans and logs have their own independent presentation patterns, leading to a fragmented experience.

## Scope

* Change the default rate aggregation unit from per-second to per-minute
* Align metrics, spans, and logs to use the same labeling and aggregation conventions
* Ensure tooltip copy, axis labels, and series names are all consistent across these three surfaces

## Dependencies

Related: [ENG-7119](https://linear.app/getsentry/issue/ENG-7119/metrics-chart-tooltip-shows-wrong-unit-label-and-duplicates-entries) (metrics tooltip showing wrong unit labels and duplicate annotations)

Action taken on behalf of David Cramer.

No files, tests, or entry points are named in the issue. Start by locating the aggregation presentation code for metrics, spans, and logs, then compare their defaults, tooltip copy, axis labels, and series names. Done means all three surfaces use per-minute by default and consistent naming and labeling.

Written by the indexing model from the issue text.