Revert "Let generic-worker verify run-task/fetch-content integrity (taskcluster#666)"

This causes failures because not all tasks have a direct dependency on the
decision task, but generic-worker insists on that dependency existing
when mounting an artifact from a task.  So go back to mounting by url.

This reverts commit f85ff32.

Author: jcristau

src/taskgraph/transforms/run/run_task.py

@@ -6,9 +6,7 @@
 """
 
 import dataclasses
-import hashlib
 import os
-from pathlib import Path
 
 from voluptuous import Any, Optional, Required
 
@@ -27,9 +25,6 @@
     "powershell": ["powershell.exe", "-ExecutionPolicy", "Bypass"],
 }
 
-RUN_TASK_PATH = Path(__file__).parent.parent.parent / "run-task" / "run-task"
-FETCH_CONTENT_PATH = Path(__file__).parent.parent.parent / "run-task" / "fetch-content"
-
 run_task_schema = Schema(
     {
         Required("using"): "run-task",
@@ -174,14 +169,10 @@ def generic_worker_run_task(config, task, taskdesc):
     common_setup(config, task, taskdesc, command)
 
     worker.setdefault("mounts", [])
-    run_task_sha256 = hashlib.sha256(RUN_TASK_PATH.read_bytes()).hexdigest()
-    fetch_content_sha256 = hashlib.sha256(FETCH_CONTENT_PATH.read_bytes()).hexdigest()
     worker["mounts"].append(
         {
             "content": {
-                "taskId": {"task-reference": "<decision>"},
-                "artifact": "public/run-task",
-                "sha256": run_task_sha256,
+                "url": script_url(config, "run-task"),
             },
             "file": "./run-task",
         }
@@ -190,9 +181,7 @@ def generic_worker_run_task(config, task, taskdesc):
         worker["mounts"].append(
             {
                 "content": {
-                    "taskId": {"task-reference": "<decision>"},
-                    "artifact": "public/fetch-content",
-                    "sha256": fetch_content_sha256,
+                    "url": script_url(config, "fetch-content"),
                 },
                 "file": "./fetch-content",
             }

test/test_transforms_run_run_task.py

@@ -121,9 +121,7 @@ def assert_generic_worker(task):
                 {"cache-name": "checkouts", "directory": "build"},
                 {
                     "content": {
-                        "artifact": "public/run-task",
-                        "sha256": "581ca6876fac84fa2dd8e8c2c18677d790890e9675229fd34c912c937ae19fae",
-                        "taskId": {"task-reference": "<decision>"},
+                        "url": "https://tc-tests.localhost/api/queue/v1/task/<TASK_ID>/artifacts/public/run-task"
                     },
                     "file": "./run-task",
                 },