Further enhance adaptive reads in Kinesis Connector to depend on run loop time

In FLINK-9692, we introduced the ability for the shardConsumer to adaptively read more records based on the current average record size to optimize the 2 Mb/sec shard limit. The feature maximizes  maxNumberOfRecordsPerFetch of 5 reads/sec (as prescribed by Kinesis limits). In the case where applications take more time to process records in the run loop, they are no longer able to read at a frequency of 5 reads/sec (even though their fetchIntervalMillis maybe set to 200 ms). In such a scenario, the maxNumberOfRecordsPerFetch should be calculated based on the time that the run loop actually takes as opposed to fetchIntervalMillis.