Fix: Prevent automatic service installation

Currently tests fail as the configuration file is not set-up properly and
service is enabled by default.
Remove automatic systemd service installation to prevent starting the
agent before user configured it.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

data/apertis-hawkbit-agent.service.in

 [Unit]
 Description=Apertis hawkBit agent
+ConditionPathExists=/etc/apertis-hawkbit-agent.ini
 
 [Service]
 ExecStart=@libexecdir@/apertis-hawkbit-agent

debian/rules

@@ -11,3 +11,6 @@ export LC_ALL=C.UTF-8
 
 %:
 	dh $@ --buildsystem=meson
+
+override_dh_systemd_enable:
+	dh_systemd_enable --name=apertis-hawkbit-agent --no-enable