Fix log level from INFO to ERROR when Change Stream failed

[HyunSangHan]

Hi, Team!

I believe, failure of Change Stream is a fatal event to MongoSource Connector users. Therefore, not the info level, but the error level log is required.

In my experience, I realized too late that my Mongo Source Connector had lost its functionality because this important log was at info level.

The log was:

INFO An exception occurred when trying to get the next item from the Change Stream: Query failed with error code 286 and error message 'Error on remote shard **.***.**.**:***** :: caused by :: Resume of change stream was not possible, as the resume point may no longer be in the oplog.' on server **.***.**.**:***** (com.mongodb.kafka.connect.source.MongoSourceTask:597)