[Fleet][EPM] Restore es-storage-related commits

[jfsiii]

Summary

This restores the es-storage-related features which were removed by commit 70fbe91 (#85942)

[elasticmachine]

Pinging @elastic/ingest-management (Team:Ingest Management)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 6f392c3

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
fleet	967.4KB	967.4KB	+2.0B

Distributable file count

id	before	after	diff
default	48026	48031	+5

Page load bundle

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

id	before	after	diff
fleet	376.5KB	376.8KB	+311.0B

Saved Objects .kibana field count

Every field in each saved object type adds overhead to Elasticsearch. Kibana needs to keep the total field count below Elasticsearch's default limit of 1000 fields. Only specify field mappings for the fields you wish to search on or query. See https://www.elastic.co/guide/en/kibana/master/development-plugin-saved-objects.html#_mappings

id	before	after	diff
epm-packages	15	18	+3
epm-packages-assets	-	8	+8
total			+11

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

[kevinlog]

LGTM

[jfsiii]

thanks, @kevinlog !

[kibanamachine]

Friendly reminder: Looks like this PR hasn’t been backported yet.
To create backports run node scripts/backport --pr 87183 or prevent reminders by adding the backport:skip label.