[FAB-7928] Eventhub reg. unexpectedly fails
[FAB-7928] Eventhub reg. unexpectedly fails

Eventhub registrations unexpectedly fail when peer.events.timewindow
is not set. This CR adds a default value of 15 minutes for the time
window to ensure that the peer does not default to 0 seconds, which
makes it impossible to register successfully.

Change-Id: I03b5ddda952bb4b62995f001202d94c7a7c262ee
Signed-off-by: Will Lahti <f19a2779710675aad3df5c81e4ecfde11707e3aa@us.ibm.com>

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