Fix dispose not being invoked #3629

Job	Run time
Windows-Default	14m 0s
Windows-SqlServer	8m 10s
Windows-AzureServiceBus	7m 14s
Windows-RabbitMQ	7m 56s
Windows-AzureStorageQueues	6m 36s
Windows-MSMQ	6m 12s
Windows-SQS	4m 49s
Windows-PrimaryRavenAcceptance	14m 22s
Windows-PrimaryRavenPersistence	7m 32s
Linux-Default	10m 1s
Linux-SqlServer	3m 54s
Linux-AzureServiceBus	7m 8s
Linux-RabbitMQ	4m 41s
Linux-AzureStorageQueues	4m 14s
Linux-SQS	3m 4s
Linux-PrimaryRavenAcceptance	12m 52s
Linux-PrimaryRavenPersistence	6m 0s
	2h 8m 45s

Provide feedback