ci: Scope RELEASE env to editor-ui turbo task (no-changelog) (backport to 1.x)

[n8n-assistant]

Description

Backport of #29585 to 1.x.

Checklist for the author (@shortstacked) to go through.

• Review the backport changes
• Fix possible conflicts
• Merge to target branch

After this PR has been merged, it will be picked up in the next patch release for release track.

Original description

Summary

RELEASE was configured in turbo's globalEnv, which meant every package's build cache was invalidated during release-publish — even though only editor-ui reads the variable (for minification, sourcemaps, Sentry upload, and legacy polyfills).

This moves RELEASE to a package-scoped n8n-editor-ui#build task in turbo.json, so that:

• All other packages get turbo cache hits from ci-master builds during release-publish
• editor-ui still correctly rebuilds when the release version changes

This should resolve the npm publish stage cache timeouts in the release workflow.

Review / Merge checklist

• I have seen this code, I have run this code, and I take responsibility for this code.
• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.

[n8n-assistant]

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin backport-29585-to-1.x
git worktree add --checkout .worktree/backport-29585-to-1.x backport-29585-to-1.x
cd .worktree/backport-29585-to-1.x
git reset --hard HEAD^
git cherry-pick -x 67f621519e73ad9fa2913b0fd8f977271f0cac1f
git push --force-with-lease