Remove deprecated Entity Store v1 ENRICH from Graph

[albertoblaz]

Summary

Closes https://github.com/elastic/security-team/issues/16326.

Checklist

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• 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.
• Flaky Test Runner was used on any tests changed
• 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

No risk, v1 ENRICH was deprecated and we either enrich via v2 + lookup mode or default to nulls

[elasticmachine]

💔 Build Failed

• Buildkite Build
• Commit: 360980b
• Kibana Serverless Image: docker.elastic.co/kibana-ci/kibana-serverless:pr-259832-360980bafa05

Failed CI Steps

• Post-Build

Metrics [docs]

‼️ ERROR: no builds found for mergeBase sha [848aa2a]

cc @albertoblaz

[elasticmachine]

Pinging @elastic/contextual-security-apps (Team:Cloud Security)