Fix cohere model input interface cannot validate cohere input issue (opensearch-project#2847)

* Fix cohere model input interface cannot validate cohere input issue

Signed-off-by: b4sjoo <sicheng.song@outlook.com>

* Clean out comments

Signed-off-by: b4sjoo <sicheng.song@outlook.com>

---------

Signed-off-by: b4sjoo <sicheng.song@outlook.com>

Author: b4sjoo

common/src/main/java/org/opensearch/ml/common/utils/ModelInterfaceUtils.java

@@ -42,10 +42,7 @@ public class ModelInterfaceUtils {
         + "            \"type\": \"object\",\n"
         + "            \"properties\": {\n"
         + "                \"texts\": {\n"
-        + "                    \"type\": \"array\",\n"
-        + "                    \"items\": {\n"
-        + "                        \"type\": \"string\"\n"
-        + "                    }\n"
+        + "                    \"type\": \"string\"\n"
         + "                }\n"
         + "            },\n"
         + "            \"required\": [\n"