mongo的表数量大于2^31-1时入仓异常

integer conv to double err when mongo one collection data count max 2^31-1。

当mongo数据小于等于2^31-1时,mongo-client返回的为integer类型
当mongo数据大于2^31-1时,超过integer最大上限,mongo-client返回的为double类型。
所以需要判断类型，再做转换。不能统一用integer进行转换。

Start at the MongoDB reader's collection-count conversion where mongo-client values are converted to integer, and inspect how the count is obtained. Reproduce the case above 2^31-1 and verify that both integer and double responses are handled without the ingestion error.

Written by the indexing model from the issue text.