fix(IoT): Fixing race conditions during cleanup in `AWSIoTStreamThread` #704

Job	Run time
validation	1s
Integration Test (AWSMobileClient)	12m 8s
Integration Test (AWSAutoScaling)	3m 58s
Integration Test (AWSCloudWatch)	4m 31s
Integration Test (AWSComprehend)	3m 17s
Integration Test (AWSCore)	8m 22s
Integration Test (AWSDynamoDB)	7m 25s
Integration Test (AWSEC2)	4m 31s
Integration Test (AWSElasticLoadBalancing)	3m 53s
Integration Test (AWSIoT)	17m 16s
Integration Test (AWSKMS)	4m 57s
Integration Test (AWSKinesis)	5m 10s
Integration Test (AWSKinesisVideoSignaling)	13m 7s
Integration Test (AWSLambda)	4m 58s
Integration Test (AWSLex)	6m 47s
Integration Test (AWSPinpoint)	15m 13s
Integration Test (AWSPolly)	6m 48s
Integration Test (AWSRekognition)	5m 52s
Integration Test (AWSS3)	14m 3s
Integration Test (AWSSES)	4m 7s
Integration Test (AWSSNS)	3m 48s
Integration Test (AWSSQS)	3m 47s
Integration Test (AWSTextract)	5m 34s
Integration Test (AWSTranscribe)	7m 45s
Integration Test (AWSTranscribeStreaming)	6m 48s
Integration Test (AWSTranslate)	3m 51s
	2h 57m 57s

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