Add new query stats metrics to track prometheus querystats

[SungJin1212]

What this PR does: Add new query stats metrics cortex_query_total_queryable_samples_total and cortex_query_peak_samples. These track TotalQueryableSamples and PeakSamples for each in https://github.com/prometheus/prometheus/blob/main/util/stats/query_stats.go

Which issue(s) this PR fixes: Fixes

Checklist

• [x] Tests updated
• [ ] Documentation added
• [x] CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[SungJin1212]

@yeya24 Could you please take a look?

[SungJin1212]

@alanprot @friedrichg could you please take a look? :)