feat: replace spiffe-helper sidecar with direct go-spiffe SDK call for operator JWT-SVID auth

[Alan-Cha]

Problem

PR #473 added a spiffe-helper sidecar container to the operator pod for fetching JWT-SVIDs. This sidecar references ghcr.io/kagenti/kagenti-extensions/spiffe-helper, but that image is not published by the kagenti-extensions automated build pipeline (which only builds authbridge variants). The image exists at :latest from a historical publish, but there is no active pipeline maintaining versioned tags.

The current state in main uses a hardcoded :latest which is fragile and non-reproducible.

Better approach

The operator already uses the go-spiffe SDK (github.com/spiffe/go-spiffe/v2) for verifiedFetch via workloadapi.NewX509Source. The same workloadapi.Client exposes FetchJWTSVID(ctx, jwtsvid.Params) which can fetch a JWT-SVID on demand directly from the SPIRE workload API socket — no sidecar, no external image, no file on disk.

This would:

• Eliminate the external image dependency entirely
• Remove the spiffe-helper sidecar container and associated volumes from the operator deployment
• Fetch JWT-SVIDs on demand per reconcile rather than relying on a file refreshed by a sidecar
• Reuse the existing --verified-fetch-spiffe-socket flag (or a shared --spiffe-socket flag)

Work required

1. Update ClientRegistrationReconciler to accept a SpiffeSocket string field instead of JWTSVIDPath
2. In the SPIFFE auth path, create a workloadapi.Client and call FetchJWTSVID(ctx, jwtsvid.Params{Audience: keycloakRealmIssuerURL})
3. Remove --jwt-svid-path flag from cmd/main.go; reuse or rename --verified-fetch-spiffe-socket
4. Remove the spiffe-helper sidecar, jwt-svid emptyDir volume, spiffe-helper-config ConfigMap, and configmap-spiffe-helper.yaml template from the chart
5. Remove spiffe.operatorAuth.spiffeHelper values block

Related

• PR Feat(operator): implement SPIFFE JWT-SVID authentication for client registration #473 (introduced the sidecar)
• PR Fix(charts+controller): SPIFFE auth follow-up — jwtAudience cleanup, credential secret skip, tag fix #476 (temporary revert to :latest while this is addressed)