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

[kibanamachine]

Backport

This will backport the following commits from main to 8.16:

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

Questions ?

Please refer to the Backport tool documentation

[elasticmachine]

:green_heart: Build Succeeded

• Buildkite Build
• Commit: c2598b676a62f744f30b451d4379b6477c453fea

Metrics [docs]

✅ unchanged

cc @ilyannn