[7.x] [Fleet] Have EPR register new categories / Show category counts (#114429)

[thomasneirynck]

Backports the following commits to 7.x:

• [Fleet] Have EPR register new categories / Show category counts ([Fleet] Have EPR register new categories / Show category counts #114429)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 89d8f9e
• Storybooks Preview

Metrics [docs]

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
customIntegrations	77	75	-2
fleet	1109	1110	+1
total			-1

Async chunks

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

id	before	after	diff
fleet	628.0KB	628.1KB	+103.0B

Page load bundle

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

id	before	after	diff
customIntegrations	6.4KB	6.4KB	-38.0B

Unknown metric groups

API count

id	before	after	diff
customIntegrations	95	91	-4
fleet	1209	1210	+1
total			-3

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