[Lens as code] Ensure unassigned_color transformation

[walterra]

Summary

Part of #257034.

Updates API payload properties unassigned_color to follow the snake_case convention.

This jq command is able to identify camelCase properties in the OAS docs:

jq -r '.. | objects | select(has("properties")) | .properties | to_entries[] | select(.key | test("[a-z][A-Z]")) | .key' oas_docs/bundle.json | sort -u

It identifies unassignedColor without this PR. No other camelCase properties are left with this PR.

Checklist

• Unit or functional tests were updated or added to match the most common scenarios
• This was checked for breaking HTTP API changes, and any breaking changes have been approved by the breaking-change committee. The release_note:breaking label should be applied in these situations.
• The PR description includes the appropriate Release Notes section, and the correct release_note:* label is applied per the guidelines
• Review the backport guidelines and apply applicable backport:* labels.

Identify risks

Low risk, API has not been released.

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[walterra]

closing in favour of #259636

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 9f2e4ab

Metrics [docs]

Async chunks

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

id	before	after	diff
agentBuilder	660.3KB	660.3KB	+3.0B
cases	2.0MB	2.0MB	+3.0B
dashboard	842.2KB	842.2KB	+3.0B
dashboardAgent	178.5KB	178.5KB	+3.0B
discover	1.6MB	1.6MB	+3.0B
infra	1.3MB	1.3MB	+3.0B
lens	2.0MB	2.0MB	+5.0B
observability	2.0MB	2.0MB	+3.0B
observabilityAIAssistantApp	326.4KB	326.4KB	+3.0B
securitySolution	11.4MB	11.4MB	+1.0B
unifiedDocViewer	420.9KB	420.9KB	+3.0B
total			+33.0B

Page load bundle

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

id	before	after	diff
securitySolution	174.1KB	174.1KB	+6.0B

History

• 💔 Build #416822 failed c4cbff7

cc @walterra