Fix failing OpenSearch IT and disable Mistral function calling IT

- PaymentStatusFunctionCallingIT in org.springframework.ai.mistralai.api.tool
  is failing.  Needs investigation.
  See https://github.com/spring-projects/spring-ai/issues/1853
- OpenSearchVectorStoreWithOllamaIT updated to pull model if not available.

models/spring-ai-mistral-ai/src/test/java/org/springframework/ai/mistralai/api/tool/PaymentStatusFunctionCallingIT.java

@@ -24,6 +24,7 @@ import java.util.function.Function;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.EnabledIfEnvironmentVariable;
 import org.slf4j.Logger;
@@ -52,6 +53,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Christian Tzolov
  * @since 0.8.1
  */
+@Disabled("See https://github.com/spring-projects/spring-ai/issues/1853")
 @EnabledIfEnvironmentVariable(named = "MISTRAL_AI_API_KEY", matches = ".+")
 public class PaymentStatusFunctionCallingIT {