terraform/environment: increase max auto scaling worker count

Change-Id: I6a9ef2e0262c54fc3dd625d31db8bec529365a7d
Reviewed-on: https://go-review.googlesource.com/c/pkgsite-metrics/+/708375
Auto-Submit: Ethan Lee <ethanalee@google.com>
Reviewed-by: Markus Kusano <kusano@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

terraform/environment/worker.tf

diff --git a/terraform/environment/worker.tf b/terraform/environment/worker.tf
index b3bf3c2..ce687aa 100644
--- a/terraform/environment/worker.tf
+++ b/terraform/environment/worker.tf
@@ -184,7 +184,7 @@
     metadata {
       annotations = {
         "autoscaling.knative.dev/minScale"         = "10"
-        "autoscaling.knative.dev/maxScale"         = each.value == "us-central1" ? "2500" : "625"
+        "autoscaling.knative.dev/maxScale"         = each.value == "us-central1" ? "3738" : "625"
         "run.googleapis.com/cloudsql-instances"    = local.pkgsite_db
         "run.googleapis.com/execution-environment" = "gen2"
       }