Fix release workflow to work with immutable releases setting (#1650)

A repo setting change enabled immutable releases, which prevents
uploading assets to a release once it's published. Creating the
release as a draft here lets goreleaser upload all assets first,
then publish as its final step.

Change-Type: fix
Release-Note: no
Audience: internal
Impact: medium
Breaking: false

Co-authored-by: Claude <noreply@anthropic.com>

Author: dopey

.github/workflows/release.yml

@@ -66,7 +66,7 @@ jobs:
         with:
           tag_name: ${{ github.ref_name }}
           name: Release ${{ github.ref_name }}
-          draft: false
+          draft: true
           prerelease: ${{ steps.is_prerelease.outputs.IS_PRERELEASE }}
 
   goreleaser: