[7.x] [Search] Search batching using bfetch (again) (#84043)

[lizozom]

Backports the following commits to 7.x:

• [Search] Search batching using bfetch (again) ([Search] Search batching using bfetch (again) #84043)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 8866112

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
bfetch	20	21	+1

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
bfetch	18.6KB	20.0KB	+1.4KB
data	974.5KB	974.1KB	-417.0B
dataEnhanced	35.2KB	35.2KB	+28.0B
total			+1.0KB

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream