devtools/docker: remove GO_DISCOVERY_E2E_ENVIRONMENT

Change-Id: If53213726bb5b68ab704a535b59fe4fbee8f3a69
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/345349
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
diff --git a/devtools/docker/compose.yaml b/devtools/docker/compose.yaml
index e35125d..9604eaa 100644
--- a/devtools/docker/compose.yaml
+++ b/devtools/docker/compose.yaml
@@ -64,7 +64,6 @@
       - CI=true
       - GO_DISCOVERY_E2E_BASE_URL=http://frontend:8080
       - GO_DISCOVERY_E2E_CHROME_URL=ws://chrome:${GO_DISCOVERY_E2E_TEST_PORT:-3000}
-      - GO_DISCOVERY_E2E_ENVIRONMENT=ci
       - WAITFORIT_TIMEOUT=300
     entrypoint: ./third_party/wait-for-it/wait-for-it.sh frontend:8080 -- npx jest
     command: e2e