Move StartLimit* options to unit section

The StartLimitBurst and StartLimitIntervalSec options belong to the
[Unit] section, otherwise they are ignored in [Service]:

> Unknown key 'StartLimitIntervalSec' in section [Service], ignoring.

When using [Unit], the limits are properly set:

  apex% systemctl show power-policy.service | grep StartLimit
  StartLimitIntervalUSec=10min
  StartLimitBurst=10
  StartLimitAction=none

m/apex/configuration.nix

@@ -5,12 +5,9 @@
     ../common/xeon.nix
     ../common/ssf/hosts.nix
     ../module/ceph.nix
-    ../module/power-policy.nix
     ./nfs.nix
   ];
 
-  power.policy = "always-on";
-
   # Don't install grub MBR for now
   boot.loader.grub.device = "nodev";
 

m/common/base.nix

@@ -3,6 +3,7 @@
   # Includes the basic configuration for an Intel server.
   imports = [
     ./base/agenix.nix
+    ./base/always-power-on.nix
     ./base/august-shutdown.nix
     ./base/boot.nix
     ./base/env.nix
@@ -11,7 +12,6 @@
     ./base/net.nix
     ./base/nix.nix
     ./base/ntp.nix
-    ./base/power-policy.nix
     ./base/rev.nix
     ./base/ssh.nix
     ./base/users.nix

m/common/base/always-power-on.nix

@@ -0,0 +1,8 @@
+{
+  imports = [
+    ../../module/power-policy.nix
+  ];
+
+  # Turn on as soon as we have power
+  power.policy = "always-on";
+}

m/common/base/power-policy.nix

@@ -1,9 +0,0 @@
-{
-  imports = [
-    ../../module/power-policy.nix
-  ];
-
-  # By default, keep the machines off as we don't know if the AC will be working
-  # once the electricity comes back.
-  power.policy = "always-off";
-}

m/fox/configuration.nix

@@ -6,11 +6,8 @@
     ../common/xeon/console.nix
     ../module/emulation.nix
     ../module/nvidia.nix
-    ../module/power-policy.nix
   ];
 
-  power.policy = "always-on";
-
   # Don't turn off on August as UPC has different dates.
   # Fox works fine on power cuts.
   systemd.timers.august-shutdown.enable = false;

m/raccoon/configuration.nix

@@ -7,12 +7,9 @@
     ../module/debuginfod.nix
     ../module/ssh-hut-extern.nix
     ../module/nvidia.nix
-    ../module/power-policy.nix
     ../eudy/kernel/perf.nix
   ];
 
-  power.policy = "always-on";
-
   # Don't install Grub on the disk yet
   boot.loader.grub.device = "nodev";