[Bug-FE][UI Next][V1.0.0-Alpha] Fix the datepicker panel up and down in start modal. (#9267)

dolphinscheduler-ui-next/src/views/projects/workflow/definition/components/start-modal.tsx

@@ -363,6 +363,7 @@ export default defineComponent({
                     type='datetimerange'
                     clearable
                     v-model:value={this.startForm.startEndTime}
+                    placement='top'
                   />
                 </NFormItem>
               </NSpace>