Add RemainAfterExit=yes to plymouth's systemd service files

All plymouth's systemd unit files are meant to only run once, either during
boot or during shutdown/restart.

Certain events cause systemd to recheck the dependency try between systemd
units. Systemd had a bug before the 245 release which caused this check to
sometimes not restart exited services for which the dependencies are met.

Systemd 245 fixes this, this is causing problems with plymouth.
When the conditions are met for systemd to recheck the dependencies;
and the plymouthd started by plymouth-start.service has exited;
then systemd will restart the plymouth-start unit, causing plymouthd to
take over tty1 after boot. This is causing various problems, also see:

https://bugzilla.redhat.com/show_bug.cgi?id=1803293

Since all plymouth's systemd units are intended to run only once, they
all should be marked as remaining after exit by adding:
"RemainAfterExit=yes" to them. This causes systemd to still consider them
running after e.g. plymouthd has exited, as long as they have started
successfully. This fixes systemd restarting plymouth's units when it
should not do so.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1803293
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1807771
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

systemd-units/plymouth-halt.service.in

@@ -10,3 +10,4 @@ ConditionVirtualization=!container
 ExecStart=@PLYMOUTH_DAEMON_DIR@/plymouthd --mode=shutdown --attach-to-session
 ExecStartPost=-@PLYMOUTH_CLIENT_DIR@/plymouth show-splash
 Type=forking
+RemainAfterExit=yes

systemd-units/plymouth-kexec.service.in

@@ -10,3 +10,4 @@ ConditionVirtualization=!container
 ExecStart=@PLYMOUTH_DAEMON_DIR@/plymouthd --mode=shutdown --attach-to-session
 ExecStartPost=-@PLYMOUTH_CLIENT_DIR@/plymouth show-splash
 Type=forking
+RemainAfterExit=yes

systemd-units/plymouth-poweroff.service.in

@@ -10,3 +10,4 @@ ConditionVirtualization=!container
 ExecStart=@PLYMOUTH_DAEMON_DIR@/plymouthd --mode=shutdown --attach-to-session
 ExecStartPost=-@PLYMOUTH_CLIENT_DIR@/plymouth show-splash
 Type=forking
+RemainAfterExit=yes

systemd-units/plymouth-quit-wait.service.in

@@ -5,4 +5,5 @@ After=rc-local.service plymouth-start.service systemd-user-sessions.service
 [Service]
 ExecStart=-@PLYMOUTH_CLIENT_DIR@/plymouth --wait
 Type=oneshot
+RemainAfterExit=yes
 TimeoutSec=0

systemd-units/plymouth-quit.service.in

@@ -5,4 +5,5 @@ After=rc-local.service plymouth-start.service systemd-user-sessions.service
 [Service]
 ExecStart=-@PLYMOUTH_CLIENT_DIR@/plymouth quit
 Type=oneshot
+RemainAfterExit=yes
 TimeoutSec=20

systemd-units/plymouth-read-write.service.in

@@ -8,3 +8,4 @@ ConditionPathExists=!/etc/initrd-release
 [Service]
 ExecStart=-@PLYMOUTH_CLIENT_DIR@/plymouth update-root-fs --read-write
 Type=oneshot
+RemainAfterExit=yes

systemd-units/plymouth-reboot.service.in

@@ -10,3 +10,4 @@ ConditionVirtualization=!container
 ExecStart=@PLYMOUTH_DAEMON_DIR@/plymouthd --mode=reboot --attach-to-session
 ExecStartPost=-@PLYMOUTH_CLIENT_DIR@/plymouth show-splash
 Type=forking
+RemainAfterExit=yes

systemd-units/plymouth-start.service.in

@@ -11,5 +11,6 @@ ConditionVirtualization=!container
 ExecStart=@PLYMOUTH_DAEMON_DIR@/plymouthd --mode=boot --pid-file=@plymouthruntimedir@/pid --attach-to-session
 ExecStartPost=-@PLYMOUTH_CLIENT_DIR@/plymouth show-splash
 Type=forking
+RemainAfterExit=yes
 KillMode=none
 SendSIGKILL=no

systemd-units/plymouth-switch-root.service.in

@@ -6,6 +6,7 @@ Before=initrd-switch-root.service
 
 [Service]
 Type=oneshot
+RemainAfterExit=yes
 ExecStart=-@PLYMOUTH_CLIENT_DIR@/plymouth update-root-fs --new-root-dir=/sysroot
 StandardInput=null
 StandardOutput=null