fix: replace uses of Parameters.is_try() with level check

In the Github world, what is considered "try" or not is much less
defined than it is on hgmo. Currently we have "enterprise-firefox-try",
"firefox-dev" and "staging-firefox" that are all "try-like" in that they
will run tasks on any arbitrary branch push.

We can no longer rely on the magic string "try" being present in the
repo name to determine this, and imo nor should we ever have been.

At least in this repo, all uses of `is_try()` are probably better off
just using `level == 1` instead.

Bug: 2044330

Author: ahal

src/taskgraph/transforms/docker_image.py

@@ -130,7 +130,7 @@ def fill_template(config, tasks):
                 "artifact_prefix": "public",
             },
             "always-target": True,
-            "expires-after": expires if config.params.is_try() else "1 year",
+            "expires-after": expires if config.params["level"] == "1" else "1 year",
             "scopes": [],
             "run-on-projects": [],
             "worker-type": "images",

src/taskgraph/transforms/task.py

@@ -457,12 +457,10 @@ def build_docker_worker_payload(config, task, task_def):
         else:
             suffix = cache_version
 
-        skip_untrusted = config.params.is_try() or level == 1
-
         for cache in worker["caches"]:
             # Some caches aren't enabled in environments where we can't
             # guarantee certain behavior. Filter those out.
-            if cache.get("skip-untrusted") and skip_untrusted:
+            if cache.get("skip-untrusted") and level == 1:
                 continue
 
             name = "{trust_domain}-level-{level}-{name}-{suffix}".format(
@@ -484,7 +482,7 @@ def build_docker_worker_payload(config, task, task_def):
     if run_task and worker.get("volumes"):
         payload["env"]["TASKCLUSTER_VOLUMES"] = ";".join(sorted(worker["volumes"]))
 
-    if payload.get("cache") and skip_untrusted:  # type: ignore
+    if payload.get("cache") and level == 1:  # type: ignore
         payload["env"]["TASKCLUSTER_UNTRUSTED_CACHES"] = "1"
 
     if features:
@@ -999,7 +997,7 @@ def build_task(config, tasks):
         if "expires-after" not in task:
             task["expires-after"] = (
                 config.graph_config._config.get("task-expires-after", "28 days")
-                if config.params.is_try()
+                if config.params["level"] == "1"
                 else "1 year"
             )