tests: fix vm.run_for_stdio in some more places
tests: fix vm.run_for_stdio in some more places

When test expect to wait for remote process, use vm.run_for_stdio.
Additionally, when the call fail, (stdout, stderr) is not assigned - use
the one attached to exception object instead.

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