test: prune low-value and duplicate tests

- Remove tautological test_trainer assertions that never trained
- Drop grpo isfinite-only smokes and merge frozen-model checks via parametrize
- Merge duplicate tool_parser cases (find/streaming/factory) with parametrize
- Collapse duplicate dataset store/detect_format tests
- Remove misleading scheduler/task tests that asserted the opposite of their names
- Merge signal-handler SIGTERM/SIGINT into one parametrized case
- Drop cross-file grpo strategy duplication kept in online_strategy

tests/trainer/test_rollout.py

@@ -81,6 +81,9 @@ def test_rollout_result_inherits_raw_rollout_fields():
     assert r.prompts.shape == (2, 4)
     assert r.responses.shape == (2, 3, 5)
     assert r.prompt_mask.shape == (2, 4)
+    # RolloutResult must carry every RawRollout field.
+    raw_fields = {f for f in RawRollout.__dataclass_fields__}
+    assert raw_fields.issubset(set(RolloutResult.__dataclass_fields__))
 
 
 def test_base_reward_model_is_abstract():