[7.x] [nit][pre-req] Strongly-type Shipper and Category (#114412)

[kibanamachine]

Backports the following commits to 7.x:

• [nit][pre-req] Strongly-type Shipper and Category ([nit][pre-req] Strongly-type Shipper and Category #114412)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 6aad6e4
• 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	78	77	-1

Page load bundle

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

id	before	after	diff
customIntegrations	6.1KB	6.4KB	+292.0B

Unknown metric groups

API count

id	before	after	diff
customIntegrations	85	95	+10

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

cc @clintandrewhall