[7.x] [dashboard][labs] Defer loading panels below the fold (#99880)

[kibanamachine]

Backports the following commits to 7.x:

• [dashboard][labs] Defer loading panels below the fold ([dashboard][labs] Defer loading panels below the fold #99880)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: b6bdc15
• Storybooks Preview

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
dashboard	217	218	+1
presentationUtil	98	102	+4
total			+5

Public APIs missing comments

Total count of every public API that lacks a comment. Target amount is 0. Run node scripts/build_api_docs --plugin [yourplugin] --stats comments for more detailed information.

id	before	after	diff
dashboard	126	128	+2
presentationUtil	96	107	+11
total			+13

Async chunks

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

id	before	after	diff
dashboard	138.7KB	139.8KB	+1.1KB

Page load bundle

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

id	before	after	diff
dashboard	325.0KB	327.9KB	+2.8KB
presentationUtil	41.4KB	43.7KB	+2.3KB
total			+5.2KB

Unknown metric groups

API count

id	before	after	diff
dashboard	138	140	+2
presentationUtil	98	109	+11
total			+13

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

cc @clintandrewhall