code: func DisableGC(ctx sessionctx.Context) error {
  	sql := fmt.Sprintf(insertVariableValueSQL, "tikv_gc_enable", "false", "Current GC enable status")
  	_, _, err := ctx.(sqlexec.RestrictedSQLExecutor).ExecRestrictedSQL(ctx, sql)
  	return errors.Trace(err)
  }
docs: // DisableGC will disable GC enable variable.