Go: fix db alignment (#16964)

### Summary

Align go db schema with python

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Signed-off-by: Jin Hai <haijin.chn@gmail.com>

internal/handler/document.go

@@ -1417,7 +1417,7 @@ func (h *DocumentHandler) ListIngestionTasks(c *gin.Context) {
 }
 
 type StartParseDocumentsRequest struct {
-	DatasetID string   `json:"dataset_id" binding:"required"`
+	DatasetID string   `json:"dataset_id"`
 	Documents []string `json:"documents" binding:"required"`
 }