Fix collector healthcheck: use wget instead of curl

The otel-collector-contrib image is Alpine-based and doesn't include
curl. Switch the healthcheck to wget --spider which is available in
the base image.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker/telemetry/docker-compose.workload.yaml

@@ -47,7 +47,7 @@ services:
     networks:
       - workload-net
     healthcheck:
-      test: ["CMD", "curl", "-f", "http://localhost:13133/"]
+      test: ["CMD", "wget", "--spider", "-q", "http://localhost:13133/"]
       interval: 5s
       timeout: 3s
       retries: 10