fix(tests): update image placeholder assertions for new non-descriptive text

The _strip_image_content methods now use a fixed non-descriptive
placeholder instead of path-derived text. Update the 3 existing
test_provider_retry assertions to match the new placeholder format.

tests/providers/test_provider_retry.py

@@ -309,7 +309,7 @@ async def test_non_transient_error_with_images_retries_without_images() -> None:
         content = msg.get("content")
         if isinstance(content, list):
             assert all(b.get("type") != "image_url" for b in content)
-            assert any("[image: /media/test.png]" in (b.get("text") or "") for b in content)
+            assert any("not delivered" in (b.get("text") or "").lower() for b in content)
 
 
 @pytest.mark.asyncio
@@ -327,7 +327,7 @@ async def test_successful_image_retry_mutates_original_messages_in_place() -> No
     content = messages[0]["content"]
     assert isinstance(content, list)
     assert all(block.get("type") != "image_url" for block in content)
-    assert any("[image: /media/test.png]" in (block.get("text") or "") for block in content)
+    assert any("not delivered" in (block.get("text") or "").lower() for block in content)
 
 
 @pytest.mark.asyncio
@@ -362,7 +362,7 @@ async def test_image_fallback_returns_error_on_second_failure() -> None:
 
 @pytest.mark.asyncio
 async def test_image_fallback_without_meta_uses_default_placeholder() -> None:
-    """When _meta is absent, fallback placeholder is '[image omitted]'."""
+    """When _meta is absent, fallback placeholder is non-descriptive."""
     provider = ScriptedProvider([
         LLMResponse(content="error", finish_reason="error"),
         LLMResponse(content="ok"),
@@ -376,7 +376,7 @@ async def test_image_fallback_without_meta_uses_default_placeholder() -> None:
     for msg in msgs_on_retry:
         content = msg.get("content")
         if isinstance(content, list):
-            assert any("[image omitted]" in (b.get("text") or "") for b in content)
+            assert any("not delivered" in (b.get("text") or "").lower() for b in content)
 
 
 @pytest.mark.asyncio