fix: do not submit value when file input is optional (#17861)

web/app/components/share/text-generation/run-once/index.tsx

   const onClear = () => {
     const newInputs: Record<string, any> = {}
     promptConfig.prompt_variables.forEach((item) => {
-      newInputs[item.key] = ''
+      if (item.type === 'text-input' || item.type === 'paragraph')
+        newInputs[item.key] = ''
+      else
+        newInputs[item.key] = undefined
     })
     onInputsChange(newInputs)
   }
   useEffect(() => {
     const newInputs: Record<string, any> = {}
     promptConfig.prompt_variables.forEach((item) => {
-      newInputs[item.key] = ''
+      if (item.type === 'text-input' || item.type === 'paragraph')
+        newInputs[item.key] = ''
+      else
+        newInputs[item.key] = undefined
     })
     onInputsChange(newInputs)
   }, [promptConfig.prompt_variables, onInputsChange])