Remove snap.subiquity.started from subiquity's After=/Requires= as it

does not fix the race condition they were intended to address and causes
subiquity to be killed when snapd refreshes subiquity (LP: #1724411)

debian/changelog

@@ -2,6 +2,9 @@ livecd-rootfs (2.478) UNRELEASED; urgency=medium
 
   * Two last minute server-live fixes:
     - Seed the subiquity snap to track the stable channel (LP: #1724410)
+    - Remove snap.subiquity.started from subiquity's After=/Requires= as it
+      does not fix the race condition they were intended to address and causes
+      subiquity to be killed when snapd refreshes subiquity (LP: #1724411)
 
  -- Michael Hudson-Doyle <mwhudson@debian.org>  Wed, 18 Oct 2017 13:22:50 +1300
 

live-build/ubuntu-server/includes.binary/overlay/lib/systemd/system/subiquity.service

@@ -1,8 +1,8 @@
 [Unit]
 Description=Subiquity, the installer for Ubuntu Server
 After=systemd-user-sessions.service plymouth-quit-wait.service
-After=rc-local.service snap.subiquity.started.service
-Requires=snapd.service snap.subiquity.started.service
+After=rc-local.service
+Requires=snapd.service
 IgnoreOnIsolate=yes
 ConditionPathExists=/dev/tty0
 ConditionPathExists=!/run/subiquity/complete