Fix Vertex AI image embedding test

Author: aIbrahiim

sdks/python/apache_beam/ml/rag/embeddings/vertex_ai_test.py

@@ -186,21 +186,17 @@ def test_image_embedding_pipeline(self):
 
   def test_image_embedding_pipeline_from_path(self):
     png_bytes = _create_png_bytes()
-    img_path = os.path.join(self.artifact_location, 'test_img.png')
-    with open(img_path, 'wb') as f:
-      f.write(png_bytes)
-
     test_items = [
         EmbeddableItem.from_image(
-            img_path, id="img1", metadata={"source": "test"}),
+            png_bytes, id="img1", metadata={"source": "test"}),
     ]
 
     expected = [
         EmbeddableItem(
             id="img1",
             embedding=Embedding(dense_embedding=[0.0] * 1408),
             metadata={"source": "test"},
-            content=Content(image=img_path)),
+            content=Content(image=png_bytes)),
     ]
 
     artifact_location = tempfile.mkdtemp(prefix='vertex_ai_img_path_')