*: fleet removes empty sections from unit files

[kayrus]

i.e. if you submit something like:

[Unit]

[Service]
ExecStart=/bin/bash -c "while true; do echo Hello, World!; sleep 1; done"

You'll get different result from the registry:

[Service]
ExecStart=/bin/bash -c "while true; do echo Hello, World!; sleep 1; done"

P.S. discovered via #1523

[kayrus]

Main point: make sha1sum failing.service output equal fleetctl cat failing.service | sha1sum