[FAB-14953] Gracefully stop goroutine in UT
[FAB-14953] Gracefully stop goroutine in UT

The test has a unit test in which a goroutine is not stopped,
and is misleading when testing for flakes.

This change set makes this goroutine stop, and switches from
using a waitgroup to using a channel.

Change-Id: Ica40785cd79a3bcd48b7db9e28d6e76cd88c8f99
Signed-off-by: yacovm <632344b5da9bd743456189af4db4b56472defb8c@il.ibm.com>

stemlending/fabric,manish-sethi/fabric-sidedb,jimthematrix/fabric,muralisrini/fabric,manish-sethi/fabric,muralisrini/fabric,manish-sethi/fabric-sidedb,jimthematrix/fabric,stemlending/fabric,stemlending/fabric,binhn/fabric,binhn/fabric,manish-sethi/fabric-sidedb,muralisrini/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,hyperledger/fabric,manish-sethi/fabric,stemlending/fabric,hyperledger/fabric,manish-sethi/fabric-sidedb,binhn/fabric