network: fix quoting in bridgescript invocation
network: fix quoting in bridgescript invocation

The deviceNames to bridge were being quoted as "[ens4 ens5]", when
they should have been just "ens4 ens5". This commit simplifies the
arguments passed to the invocation of the bridgescript.

mikemccracken/juju,mikemccracken/juju,bac/juju,waigani/juju,anastasiamac/juju,anastasiamac/juju,marcmolla/juju,mikemccracken/juju,marcmolla/juju,waigani/juju,bac/juju,ericsnowcurrently/juju,ericsnowcurrently/juju,ericsnowcurrently/juju,ericsnowcurrently/juju,waigani/juju,bac/juju,alesstimec/juju,ericsnowcurrently/juju,bac/juju,marcmolla/juju,mjs/juju,mjs/juju,marcmolla/juju,marcmolla/juju,waigani/juju,anastasiamac/juju,mjs/juju,mikemccracken/juju,anastasiamac/juju,alesstimec/juju,alesstimec/juju,bac/juju,mjs/juju,anastasiamac/juju,mjs/juju,alesstimec/juju,mikemccracken/juju,mjs/juju,alesstimec/juju,mjs/juju