project-lakitu: add ntp module in cloud-init

we use ubuntu base of cloud-init on COS, where as in ubuntu,
the chrony service runs as chrony.service but on COS it runs
as chronyd service. Ubuntu uses the default configuration at /etc/chrony.conf
but on COS, the default conf is present at /etc/chrony/chrony.conf

21.2-enable-ntp-for-cos.patch does the following
* replace chrony service with chronyd.service as per COS
* replace default conf path to be /etc/chrony/chrony.conf
* clean up the template used to generate /etc/chrony/chrony.conf
when ntp server is configured in cloud-init. This is to make conf
similar to that of COS.



BUG=b/197692631
TEST=manual validation
RELEASE_NOTE=Enable configuring NTP server using cloud-init

Change-Id: I9e1d0719cfb0ee1e0a21097340bc063679b0c559
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/22010
Reviewed-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
7 files changed