cmd/worker/Dockerfile: fix env var name

Change-Id: Ia6a42e3bfabd9a4afe0f0bc6269904b0e9c6e75b
Reviewed-on: https://go-review.googlesource.com/c/pkgsite-metrics/+/469918
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com>
diff --git a/cmd/worker/Dockerfile b/cmd/worker/Dockerfile
index 5a6df8f..8a4405b 100644
--- a/cmd/worker/Dockerfile
+++ b/cmd/worker/Dockerfile
@@ -85,6 +85,6 @@
 ENV DOCKER_IMAGE=$DOCKER_IMAGE
 
 ARG BQ_DATASET
-ENV GO_METRICS_BIGQUERY_DATASET=$BQ_DATASET
+ENV GO_ECOSYSTEM_BIGQUERY_DATASET=$BQ_DATASET
 
 CMD ["./worker"]