[Performance] Optimization for numeric and string terms aggregation queries

[vinaykpud]

Describe the bug

There are some optimizations done for numeric and string terms aggregation queries

1. optimize num agg using quick select for topN when applicable: rishabhmaurya@33336a1

2. Optimize String terms agg : rishabhmaurya@27d71e8

3. Optimize the reduce merge at coordinator: rishabhmaurya@3c25140

As part of this issue we plan to benchmark the performance improvements with this changes and product ionize

Related component

Search:Performance

Expected behavior

Improvement in the performance

Additional Details

Plugins
NA

Screenshots
NA

Host/Environment (please complete the following information):

• Tests using r5.xl host with EBS Gp3 16000 IOPS, 500Gb and 1000 throughput.

Additional context
NA