Update waagent to v2.15.0.1 and keep systemd config in sync

 * upgrades waagent to the latest version
 * syncs the systemd config, which adds memory-accounting and a dependency
   to cloud-init.service, which ensures that the waagent.service does not start
   before cloud-init has finished.

<https://github.com/Azure/WALinuxAgent/blob/v2.15.0.1/init/ubuntu/walinuxagent.service>

Author: s4heid

stemcell_builder/stages/system_azure_init/apply.sh

@@ -9,8 +9,8 @@ packages="python3 python3-pyasn1 python3-setuptools python3-distro python-is-pyt
 cloud-init linux-cloud-tools-common linux-cloud-tools-generic"
 pkg_mgr install $packages
 
-wala_release=2.14.0.1
-wala_expected_sha1=e8f30e34eedc9280531af1bb1af9efb53d1a1039
+wala_release=2.15.0.1
+wala_expected_sha1=155fd6f326a2bf2ff97b4ea2e2c83dc16a9c1768
 
 curl -L https://github.com/Azure/WALinuxAgent/archive/v${wala_release}.tar.gz > /tmp/wala.tar.gz
 sha1=$(cat /tmp/wala.tar.gz | openssl dgst -sha1  | awk 'BEGIN {FS="="}; {gsub(/ /,"",$2); print $2}')

stemcell_builder/stages/system_azure_init/assets/etc/waagent/walinuxagent.service

@@ -7,7 +7,7 @@
 [Unit]
 Description=Azure Linux Agent
 
-After=network-online.target
+After=network-online.target cloud-init.service
 Wants=network-online.target sshd.service sshd-keygen.service
 
 ConditionFileIsExecutable=/usr/sbin/waagent
@@ -22,6 +22,7 @@ ExecStart=/usr/bin/python3 -u /usr/sbin/waagent -daemon
 Restart=always
 Slice=azure.slice
 CPUAccounting=yes
+MemoryAccounting=yes
 
 [Install]
 WantedBy=multi-user.target