MQE: improve performance of subqueries when the parent query is a range query with many steps #9719
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What this PR does
This PR is a follow-up PR to #9664.
This PR improves the performance of subqueries when the parent query is a range query with many steps.
It does this by changing the behaviour of the ring buffer implementations to search forwards through the buffer to find the end of the range when a subquery is being evaluated, rather than backwards. Searching backwards makes sense for range vector selectors, where there is expected to only be one point, if any, at the end of the buffer outside the range, but for subqueries in range queries it is expected that there will be many points at the end of the buffer outside the range, so it is usually faster to search from the beginning of the buffer.
Leaving this as a draft for now while I investigate a regression for the benchmark results for range vector selectors.
Which issue(s) this PR fixes or relates to
#9664
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX].about-versioning.mdupdated with experimental features.