units: condition out a few services in the initrd

Let's make our units more robust to being added to an initrd:

1. systemd-boot-update only makes sense if sd-boot is available in /usr/
   to copy into the ESP. This is generally not the case in initrds, and
   even if it was, we shouldn't update the ESP from the initrd, but from
   the host instead.

2. The rfkill services save/restore rfkill state, but that information
   is only available once /var/ is mounted, which generally happens
   after the initrd transition.

3. utmp management is partly in /var/, and legacy anyway, hence don't
   bother with it in the initrd.

units/systemd-boot-update.service

@@ -10,6 +10,7 @@
 [Unit]
 Description=Automatic Boot Loader Update
 Documentation=man:bootctl(1)
+ConditionPathExists=!/etc/initrd-release
 
 DefaultDependencies=no
 After=local-fs.target

units/systemd-rfkill.service.in

@@ -10,6 +10,8 @@
 [Unit]
 Description=Load/Save RF Kill Switch Status
 Documentation=man:systemd-rfkill.service(8)
+ConditionPathExists=!/etc/initrd-release
+
 DefaultDependencies=no
 BindsTo=sys-devices-virtual-misc-rfkill.device
 Conflicts=shutdown.target

units/systemd-rfkill.socket

@@ -10,6 +10,7 @@
 [Unit]
 Description=Load/Save RF Kill Switch Status /dev/rfkill Watch
 Documentation=man:systemd-rfkill.socket(8)
+ConditionPathExists=!/etc/initrd-release
 
 DefaultDependencies=no
 BindsTo=sys-devices-virtual-misc-rfkill.device

units/systemd-update-utmp-runlevel.service.in

@@ -10,6 +10,8 @@
 [Unit]
 Description=Record Runlevel Change in UTMP
 Documentation=man:systemd-update-utmp-runlevel.service(8) man:utmp(5)
+ConditionPathExists=!/etc/initrd-release
+
 DefaultDependencies=no
 RequiresMountsFor=/var/log/wtmp
 Conflicts=shutdown.target

units/systemd-update-utmp.service.in

@@ -10,6 +10,7 @@
 [Unit]
 Description=Record System Boot/Shutdown in UTMP
 Documentation=man:systemd-update-utmp.service(8) man:utmp(5)
+ConditionPathExists=!/etc/initrd-release
 
 DefaultDependencies=no
 After=systemd-remount-fs.service systemd-tmpfiles-setup.service auditd.service