chore: add unified content wrapping for multimodal gemini embeddings (gemini-embedding-2) for Gemini API

PiperOrigin-RevId: 889923492

Author: speedstorm1

src/test/java/com/google/genai/TableTest.java

@@ -200,7 +200,7 @@ private static Collection<DynamicTest> createTestCases(
       String msg = " => Test skipped: replay tests are not supported for edit_image";
       return Collections.singletonList(DynamicTest.dynamicTest(testName + msg, () -> {}));
     }
-    if (testName.contains("models.embed_content.test_vertex_new_api_inline_pdf")) {
+    if (testName.contains("models.embed_content.test_new_api_inline_pdf")) {
       String msg = " => Test skipped: inline byte deserialization fails";
       return Collections.singletonList(DynamicTest.dynamicTest(testName + msg, () -> {}));
     }