[7.x] [data.search][data.indexPatterns] Expose esaggs + indexPatternLoad on the server. (#84590)

[lukeelmers]

Backports the following commits to 7.x:

• [data.search][data.indexPatterns] Expose esaggs + indexPatternLoad on the server. ([data.search][data.indexPatterns] Expose esaggs + indexPatternLoad on the server. #84590)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 766e692

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
data	603	606	+3

Distributable file count

id	before	after	diff
default	43797	43807	+10
oss	23039	23049	+10

Page load bundle

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

id	before	after	diff
data	985.9KB	989.8KB	+4.0KB
expressions	182.6KB	182.7KB	+93.0B
total			+4.0KB

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@elasticmachine merge upstream