Deprecate the existing customizable_dashboard component
### Problem to solve
The existing [customizable dashboards component](https://gitlab.com/gitlab-org/gitlab/blob/master/app/assets/javascripts/vue_shared/components/customizable_dashboard/customizable_dashboard.vue) is tightly coupled to Analytics with domain specific feature requirements that are incompatible with our modular dashboard foundations approach.
### Proposal
1. Move and/or rename the now deprecated `customizable_dashboards.vue` from Vue shared to analytics directory.
- Renaming this to `analytics_customizable_dashboard.vue` might help avoid confusion
### Related
- Replacement https://gitlab.com/gitlab-org/gitlab/-/issues/546201+s
- Analytics refactor https://gitlab.com/gitlab-org/gitlab/-/issues/542166+s
issue