Track deprecations for Localgov 3.0 (Drupal 10)

[andybroomfield]

Is your feature request related to a problem? Please describe.
If we are considering a seperate branch for Drupal 10 in the profile, it may be worth starting to track deprecations for things we want to remove, and begin marking them as such.

Describe the solution you'd like
Examples:

• Remove Localgov_skeleton
• Remove Localgov_theme
• Remove the service update panel on landing pages

[andybroomfield]

Closing this as localgov 3 released. We did remove the themes, but the service update panel hasn't had movement and would require new release of localgov_services.