[8.15] [Automatic Import] Correctly output icons in the manifest (#201139)

[kibanamachine]

Backport

This will backport the following commits from main to 8.15:

• [Automatic Import] Correctly output icons in the manifest (#201139)

Questions ?

Please refer to the Backport tool documentation

[elasticmachine]

:yellow_heart: Build succeeded, but was flaky

• Buildkite Build
• Commit: 781c94d3b8dc0a1c38a29e59106ce41657623d0e

Failed CI Steps

• Jest Tests #7

Metrics [docs]

✅ unchanged

cc @ilyannn