[Concurrent Segment Search] Supporting scripting for composite aggs

[jed326]

We have recently re-enabled concurrent segment search for composite aggs, but only when scripting is not used. This issue is to track supporting concurrent segment search for composite aggs where scripting is used.
Reference Issues and PRs:

• [BUG][Concurrent Search] Search request for top anomalies from AD plugin is failing #12331
• Disable concurrent search path for composite aggregations. #12375
• Perform buildAggregation concurrently and partially support composite aggs #12697

Issue overview: #12331 (comment)

Related component

Search:Performance