[8.0] Delete legacy URL aliases when objects are deleted or unshared (#117056)

[kibanamachine]

Backports the following commits to 8.0:

• Delete legacy URL aliases when objects are deleted or unshared (Delete legacy URL aliases when objects are deleted or unshared #117056)

[kibanamachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 967291e
• Storybooks Preview

Metrics [docs]

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
legacy-url-alias	6	7	+1

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

cc @jportner