Mimir query engine: report queries rejected due to hitting the memory consumption limit in the cortex_querier_queries_rejected_total metric

[charleskorn]

What this PR does

This PR builds on #8230, and adds incrementing the cortex_querier_queries_rejected_total{reason="max-estimated-memory-consumption-per-query"} metric when a query is rejected for exceeding the per-query memory consumption limit.

Which issue(s) this PR fixes or relates to

(none)

Checklist

• Tests updated.
• [n/a] Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• [n/a] about-versioning.md updated with experimental features.

[jhesketh]

lgtm. Minor nit: would be nice to see a test where 3 out of 4 queries fail and the counter is as we expect (make sure we don't double count them etc)

[charleskorn]

lgtm. Minor nit: would be nice to see a test where 3 out of 4 queries fail and the counter is as we expect (make sure we don't double count them etc)

Good idea, added in a0235fe