fix: trim opencode-go 422 salvage to the invariant set

Drop the bare "tool.content" pattern (any 400 mentioning tool.content in a
non-list context would be sent through the image-strip path) and the profile
flag snapshot test; the behaviour tests (classifier verdict + proactive
downgrade) already pin the contract.

tests/plugins/model_providers/test_opencode_go_profile.py

@@ -254,11 +254,3 @@ class TestOpenCodeGoFullKwargsIntegration:
         assert "extra_body" not in kwargs
         assert kwargs["reasoning_effort"] == "high"
 
-
-class TestOpenCodeGoVisionToolMessages:
-    """OpenCode Go provider profile declares supports_vision_tool_messages=False (#104731)."""
-
-    def test_supports_vision_true_and_tool_messages_false(self, opencode_go_profile):
-        assert opencode_go_profile.supports_vision is True
-        assert opencode_go_profile.supports_vision_tool_messages is False
-