fix(llm): remove multi-modal restriction on pre request check

changelog/unreleased/kong/fix-ai-proxy-multi-modal-azure.yml

@@ -0,0 +1,4 @@
+message: |
+   **AI-Proxy**: Fixed issue where multi-modal requests is blocked on azure provider. 
+type: bugfix
+scope: Plugin

kong/llm/drivers/shared.lua

@@ -604,20 +604,6 @@ function _M.resolve_plugin_conf(kong_request, conf)
 end
 
 
-local function check_multi_modal(conf, request_table)
-  if not request_table.messages or (conf.model.provider == "openai" or conf.model.provider == "bedrock" ) then
-    return true
-  end
-
-  for _, m in ipairs(request_table.messages) do
-    if type(m.content) == "table" then
-      return false
-    end
-  end
-
-  return true
-end
-
 function _M.pre_request(conf, request_table)
   -- process form/json body auth information
   local auth_param_name = conf.auth and conf.auth.param_name
@@ -636,11 +622,6 @@ function _M.pre_request(conf, request_table)
     return nil, "no plugin name is being passed by the plugin"
   end
 
-  local ok = check_multi_modal(conf, request_table)
-  if not ok then
-    return kong.response.exit("multi-modal input is not supported by current provider")
-  end
-
   -- if enabled AND request type is compatible, capture the input for analytics
   if conf.logging and conf.logging.log_payloads then
     kong.log.set_serialize_value(fmt("ai.%s.%s.%s", plugin_name, log_entry_keys.PAYLOAD_CONTAINER, log_entry_keys.REQUEST_BODY), kong.request.get_raw_body())