fix: remove misleading error about docker-worker artifacts

We're no longer using docker-worker, so this error message is
misleading. Update it with actual useful advice.

Author: ahal

src/scriptworker/cot/verify.py

@@ -728,12 +728,12 @@ async def download_cot_artifact(chain, task_id, path):
         return
 
     if path not in link.cot["artifacts"]:
+        cot_url = get_artifact_url(chain.context, link.task_id, "public/chain-of-trust.json")
         raise CoTError(
-            "path {path} not in {link_name} {task_id} chain of trust artifacts! This is likely "
-            "a bug in {task_id}: docker-worker does not fail if a declared artifact was never "
-            "generated by the task. Please download and make sure the artifact {path} is the "
-            "one you expect. If it is, then please reach out to the Release Engineering "
-            "team. For more information: https://github.com/taskcluster/taskgraph/issues/47".format(path=path, link_name=link.name, task_id=link.task_id)
+            "path {path} not in {link_name} {task_id} chain of trust artifacts! Verify {path} "
+            "is correct, was produced by task {task_id}, and is listed in {cot_url}".format(
+                path=path, link_name=link.name, task_id=link.task_id, cot_url=cot_url
+            )
         )
     url = get_artifact_url(chain.context, task_id, path)
     loggable_url = get_loggable_url(url)