[63485] Remove `show_local_breadcrumb` and `default_breadcrumb`

[HDinger]

Ticket

https://community.openproject.org/projects/design-system/work_packages/63485/github?query_id=6253

What are you trying to accomplish?

• Remove outdated show_local_breadcrumb method which is replaced by the Primer::PageHeader breadcrumb

⚠️ Should be merged after https://github.com/opf/openproject/pull/18600

[klaustopher]