Geo Replication - Update breadcrumbs to match tabs and view

Why are we doing this work

Breadcrumbs should be intuitive and a way for users at a glance to have confidence in where they are in the application and how to navigate back.

Relevant links

Follow up from conversation here: !178032 (comment 2308400280)

Screenshots

	Current	Suggested
List View
Details View (this MR)

Implementation plan

1. Remove page_title from _replication_nav.haml

2. Add page_title to replicables/index.html.haml

- page_title @replicator_class.replicable_title_plural

3. Add :set_replicator_class to the :show action in replicables_controller.rb

before_action :set_replicator_class, only: [:index, :show]

4. Update add_to_breadcrumbs and page_title in geo/replicables/show.html.haml (added in !178032 (merged))

- add_to_breadcrumbs _('Geo Sites'), admin_geo_nodes_path
- add_to_breadcrumbs @replicator_class.replicable_title_plural, site_replicables_admin_geo_node_path
- page_title @replicator.model_record_id