docs: /opt/canonical/landscape/scripts/sync_lds_releases.sh script should be removed from documentation + add removal to release notes for 25.10

Several landscape scripts have been removed from Landscape starting in 25.10. These include the sync_lds_releases.sh & report_anonymous_metrics.sh script as found [here](https://github.com/canonical/landscape-server/pull/780) and was confirmed by William Kronholm today. The scripts both call on webpages that have now been deleted including https://landscape.canonical.com/get-lds-releases & https://landscape.canonical.com/anonymous-metrics. these are no longer available due to them being taken down in conjuction with the removal of this script. This has led to some confusion for customers who are on older versions still trying to use the script. I suggest we remove these bullet points from this documentation:

- /opt/canonical/landscape/scripts/sync_lds_releases.sh

- This task verifies if there are new Landscape Server upgrades available in order to add a notification on the account page.

- /opt/canonical/landscape/scripts/report_anonymous_metrics.sh

- This task reports some anonymous metrics, such as the installed Landscape Server version.

Secondly we should add this change to the [25.10 Landscape Release Notes](https://documentation.ubuntu.com/landscape/reference/release-notes/25.10-release-notes/) as I wasn't able to find any publicly available documentation of this change. Some users may be confused as to why these scripts are missing in newer versions and although the github link above shows the changes, this is not publicly available.

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*Reported from: https://documentation.ubuntu.com/landscape/how-to-guides/backup-and-maintenance/manage-maintenance-tasks/*