Disable update-engine.service

There is a race condition between systemd and device policy manager.
Confidential VM makes systemd units slower so that policy manager
finishes its work before update-engine.service is initiated and enabled
resulting in unexpected OS update.

Device policy manager can enable update-engine.service if the metadata
for disabling auto-update is not set. So we should disable
update-engine.service in systemd and let device policy manager controls
it.

BUG=b/335549105
TEST=presubmit and validation tests
RELEASE_NOTE=None

cos-patch: bug
Change-Id: Ib3e1fb29ae02ca44f75ad0be20c361ef65bb91d0
Reviewed-on: https://cos-review.googlesource.com/c/third_party/overlays/chromiumos-overlay/+/72733
Reviewed-by: Oleksandr Tymoshenko <ovt@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
diff --git a/chromeos-base/update_engine/files/update-engine.service b/chromeos-base/update_engine/files/update-engine.service
index 716500c..521f934 100644
--- a/chromeos-base/update_engine/files/update-engine.service
+++ b/chromeos-base/update_engine/files/update-engine.service
@@ -8,6 +8,3 @@
 Slice=system-sysdaemons.slice
 Restart=on-failure
 RestartSec=5
-
-[Install]
-WantedBy=multi-user.target
diff --git a/chromeos-base/update_engine/update_engine-0.0.3-r4803.ebuild b/chromeos-base/update_engine/update_engine-0.0.3-r4804.ebuild
similarity index 98%
rename from chromeos-base/update_engine/update_engine-0.0.3-r4803.ebuild
rename to chromeos-base/update_engine/update_engine-0.0.3-r4804.ebuild
index 638b5aa..975547b 100644
--- a/chromeos-base/update_engine/update_engine-0.0.3-r4803.ebuild
+++ b/chromeos-base/update_engine/update_engine-0.0.3-r4804.ebuild
@@ -145,7 +145,6 @@
 
 	if use systemd; then
 		systemd_dounit "${FILESDIR}"/update-engine.service
-		systemd_enable_service multi-user.target update-engine.service
 	else
 		# Install upstart script
 		insinto /etc/init
diff --git a/chromeos-base/update_engine/update_engine-9999.ebuild b/chromeos-base/update_engine/update_engine-9999.ebuild
index baf25f1..4d8f67c 100644
--- a/chromeos-base/update_engine/update_engine-9999.ebuild
+++ b/chromeos-base/update_engine/update_engine-9999.ebuild
@@ -143,7 +143,6 @@
 
 	if use systemd; then
 		systemd_dounit "${FILESDIR}"/update-engine.service
-		systemd_enable_service multi-user.target update-engine.service
 	else
 		# Install upstart script
 		insinto /etc/init