plymouth: Remove the calls to plymouth message

 * messages aren't translated
 * console text is ugly
 * they are jargonny
 * they really aren't needed

https://bugs.freedesktop.org/show_bug.cgi?id=35711

units/plymouth-halt.service

@@ -14,5 +14,4 @@ DefaultDependencies=no
 [Service]
 ExecStart=/sbin/plymouthd --mode=shutdown
 ExecStartPost=-/bin/plymouth --show-splash
-ExecStartPost=-/bin/plymouth message '--text=Halting...'
 Type=forking

units/plymouth-kexec.service

@@ -14,5 +14,4 @@ DefaultDependencies=no
 [Service]
 ExecStart=/sbin/plymouthd --mode=shutdown
 ExecStartPost=-/bin/plymouth --show-splash
-ExecStartPost=-/bin/plymouth message '--text=Rebooting with kexec...'
 Type=forking

units/plymouth-poweroff.service

@@ -14,5 +14,4 @@ DefaultDependencies=no
 [Service]
 ExecStart=/sbin/plymouthd --mode=shutdown
 ExecStartPost=-/bin/plymouth --show-splash
-ExecStartPost=-/bin/plymouth message '--text=Powering Off...'
 Type=forking

units/plymouth-reboot.service

@@ -14,5 +14,4 @@ DefaultDependencies=no
 [Service]
 ExecStart=/sbin/plymouthd --mode=shutdown
 ExecStartPost=-/bin/plymouth --show-splash
-ExecStartPost=-/bin/plymouth message '--text=Rebooting...'
 Type=forking