tests/integ/network: few more code style improvement
tests/integ/network: few more code style improvement

Remove unused imports and unused variables, add some more docstrings.

marmarek/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin,QubesOS/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin