Testing result on commit 0f78c08
TLDR: Tests look good.

* Upgraded chrony on a GCE noble instance. `/etc/chrony/sources.d/ubuntu-ntp-pools.sources` was created as expected. If the user chooses to keep the local version of `/etc/chrony/chrony.conf` in this case chrony configuration is preserved as is. This is because `/etc/chrony/chrony.conf` on GCE instances does not import sources.d so the introduction of `/etc/chrony/sources.d/ubuntu-ntp-pools.sources` does not have an effect. This is an desired outcome.
* Upgraded chrony on a GCE noble instance. `/etc/chrony/sources.d/ubuntu-ntp-pools.sources` was created. Some changes made to `ubuntu-ntp-pools.sources` and then chrony was upgraded again to a version which had changes to `ubuntu-ntp-pools.sources`. This produced an ucf prompt for `ubuntu-ntp-pools.sources` as expected.
* Upgraded chrony on a GCE noble instance. `/etc/chrony/sources.d/ubuntu-ntp-pools.sources` was created. Chrony was upgraded again to a version which had changes to `ubuntu-ntp-pools.sources`. This did not produce an ucf prompt for `ubuntu-ntp-pools.sources` as expected.
* Upgraded chrony on a GCE noble instance. `/etc/chrony/sources.d/ubuntu-ntp-pools.sources` was created. Some changes made to `ubuntu-ntp-pools.sources` and then chrony was upgraded again. This did produce an ucf prompt for `ubuntu-ntp-pools.sources` as expected.
* Upgraded chrony on a GCE noble instance. `/etc/chrony/sources.d/ubuntu-ntp-pools.sources` was created. Set `chrony/configure_ubuntu_pools_in_sourcesd` to false, deleted `/etc/chrony/sources.d/ubuntu-pools-ntp.sources`. Upgraded chrony to a version which had changes to `ubuntu-ntp-pools.sources`. This did not produce an ucf prompt and `/etc/chrony/sources.d/ubuntu-pools-ntp.sources` was not created as expected.
*  Upgraded chrony on a GCE noble instance. `/etc/chrony/sources.d/ubuntu-ntp-pools.sources` was created. Set `chrony/configure_ubuntu_pools_in_sourcesd` to false, deleted `/etc/chrony/sources.d/ubuntu-pools-ntp.sources`. Upgraded chrony again. This did not produce an ucf prompt and `/etc/chrony/sources.d/ubuntu-pools-ntp.sources` was not created as expected.
* Upgraded chrony on a GCE noble instance with `chrony/configure_ubuntu_pools_in_sourcesd` set to false. `/etc/chrony/ubuntu-ntp-pools.sources` was not created as expected.
* Upgraded chrony on a GCE noble instance with `chrony/configure_ubuntu_pools_in_sourcesd` set to false. `/etc/chrony/ubuntu-ntp-pools.sources` was not created. Created `/etc/chrony/ubuntu-ntp-pools.sources` by hand and upgraded chrony again to a version which had changes to `ubuntu-ntp-pools.sources`. No ucf prompt and user version of `ubuntu-ntp-pools.sources` was deleted as expected.
*  Upgraded chrony on a GCE noble instance with `chrony/configure_ubuntu_pools_in_sourcesd` set to false. `/etc/chrony/ubuntu-ntp-pools.sources` was not created. Created `/etc/chrony/ubuntu-ntp-pools.sources` by hand and upgraded chrony again. No ucf prompt and user version of `ubuntu-ntp-pools.sources` was deleted as expected.
* Upgraded chrony on a GCE noble instance with `chrony/configure_ubuntu_pools_in_sourcesd` set to false. `/etc/chrony/ubuntu-ntp-pools.sources` was not created. Upgraded chrony again to a version which had changes to `ubuntu-ntp-pools.sources`. No ucf prompt and `/etc/chrony/ubuntu-ntp-pools.sources` was not created as expected.
* Upgraded chrony on a GCE noble instance with `chrony/configure_ubuntu_pools_in_sourcesd` set to false. `/etc/chrony/ubuntu-ntp-pools.sources` was not created. Upgraded chrony again. No ucf prompt and `/etc/chrony/ubuntu-ntp-pools.sources` was not created as expected.
* Created `/etc/chrony/ubuntu-ntp-pools.sources` identical to one in this fix on a GCE noble instance. Upgraded chrony. There was no ucf prompt for `ubuntu-ntp-pools.sources` as expected.
* Created `/etc/chrony/ubuntu-ntp-pools.sources` different from the one in this fix on a GCE noble instance. Upgraded chrony. There was an ucf prompt for `ubuntu-ntp-pools.sources` as expected.
* Upgraded chrony on an AWS noble instance. chrony time source configuration was preserved as is as expected.
* Upgraded chrony on an AWS noble instance with `chrony/configure_ubuntu_pools_in_sourcesd` set to false. The default Ubuntu time sources were omitted from `chronyc sources` as expected.
* Built a GCE 24.10 image with `chrony/configure_ubuntu_pools_in_sourcesd` set to false before chrony install. The image did not have `/etc/chrony/default-ntp-pools.sources` as expected and booted successfully.
* @jessica-youjeong from the CPC team built an EC2 that installed chrony with the fix. As EC2 images currently contain the Ubuntu time sources the debconf question was not preseeded. The EC2 image had chrony configuration as expected.