Update test-network chaincode container versions

The test-network peer configuration specifies $(TWO_DIGIT_VERSION) as
the tag for the Node and Java chaincode containers. For Fabric v3.0,
this requests fabric-nodeenv:3.0 and fabric-javaenv:3.0 Docker images to
host Node and Java chaincode respectively. These images do not exist,
which causes deployment of Node and Java chaincode to fail when using
Fabric v3.0. Fabric v3.0 continues to use fabric-nodeenv:2.5 and
fabric-javaenv:2.5.

This change updates the test-network peer configuration to explicitly
specify `2.5` as the Node and Java chaincode Docker image tags. This is
(currently) the correct version for both Fabric v2.5 and Fabric v3.0.

Signed-off-by: Mark S. Lewis <Mark.S.Lewis@outlook.com>