[MAINTENANCE] Remove unused V1 Code

[jrhoads]

Service/repository
ror-api

Describe the current state/issue
This API has fully transitioned from v1 to v2, and the v1 code is no longer used on any requests. However, the code is still part of the codebase.

Describe the desired state/solution
All references to v1, view paths, URLs, and serializers should be removed.

Additional notes
This does not remove the Elasticsearch index.

[adambuttrick]

Addressed with ror-community/ror-api#525.