Improve time for SortPreservingMerge stream / uninitiated_partitions VecDeque<usize>

[alamb]

Is your feature request related to a problem or challenge?

Both @rluvaton and I have seen

I saw this when running the following query

./datafusion-cli-filter-pushdown -c "SELECT \"WatchID\", \"ClientIP\", COUNT(*) AS c, SUM(\"IsRefresh\"), AVG(\"ResolutionWidth\") FROM hits WHERE \"SearchPhrase\" <> '' GROUP BY \"WatchID\", \"ClientIP\" ORDER BY c DESC LIMIT 10;"

Using hits.parquet: https://datasets.clickhouse.com/hits_compatible/hits.parquet

I am not sure what @rluvaton was doing when he saw it

Describe the solution you'd like

Review and see if this is a performance bottleneck we can remove

Describe alternatives you've considered

No response

Additional context

No response

[alamb]

BTW this code was added in

• Fix Possible Congestion Scenario in SortPreservingMergeExec #12302

[Rachelint]

take

[alamb]

FYI @Rachelint I think @rluvaton has a proposal on a ticket as well

• Perf: remove clone on uninitiated_partitions in SortPreservingMergeStream #15562