tests: network_topology_strategy_test: peel off redundant parentheses around token initializer
tests: network_topology_strategy_test: peel off redundant parentheses around token initializer

The token constructor is called with an extra level of parentheses. Presumably
this caused a temporary object to be constructed and then moved into the
variable being initialized, but gcc 8 complains about ambiguity.

Make it happy by stripping off the redundant parentheses.
Message-Id: <28097cd9c8dd12fd7eab3bee4ced1473693f582a@scylladb.com>

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