periodic: stop running dl3 and edsr on the portable backend

.ci/scripts/gather_test_models.py

@@ -102,6 +102,19 @@ def model_should_run_on_event(model: str, event: str) -> bool:
         return True
 
 
+def model_should_run_on_backend(model: str, backend: str) -> bool:
+    """
+    A helper function to decide whether a model should be tested on a backend.
+    """
+    # dl3 and edsr on portable have hit the 90 minute job limit on every periodic
+    # run since 2026-08-03, so they only ever report cancelled. Their xnnpack
+    # variants still cover both models and finish in about ten minutes.
+    # TODO(#21692): re-enable once portable export of these two fits in the limit.
+    if backend == "portable" and model in ("dl3", "edsr"):
+        return False
+    return True
+
+
 def model_should_run_on_target_os(model: str, target_os: str) -> bool:
     """
     A helper function to decide whether a model should be tested on a target os (linux/macos).
@@ -153,7 +166,9 @@ def export_models_for_ci() -> dict[str, dict]:
         if not model_should_run_on_event(name, event):
             continue
 
-        if not model_should_run_on_target_os(name, target_os):
+        if not model_should_run_on_target_os(
+            name, target_os
+        ) or not model_should_run_on_backend(name, backend):
             continue
 
         if backend == "xnnpack":