veyron/services/mgmt/node/impl: updating 'wait for child' timeout to 20s to see if it helps with mac jenkins test failures.
veyron/services/mgmt/node/impl: updating 'wait for child' timeout to 20s to see
if it helps with mac jenkins test failures.

Change-Id: I490680a78cc3c18b27dda9d86fe5165e44b3babe

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref