Generating Swagger/OpenAPI schema should not require generating GraphQL schema

[glennmatthews]

Environment

• Python version:
• Nautobot version: 1.3.0b2

Steps to Reproduce

1. Enable debug logging on Nautobot
2. Access /api/docs/
3. Check logs

Alternately, with #1544 in place, simply run nautobot-server spectacular --file nautobot.openapi.yaml

Expected Behavior

Rapid OpenAPI schema generation

Observed Behavior

Schema generation is relatively slow, and logs indicate that a significant amount of the time is spent generating the GraphQL schema as part of the OpenAPI schema rendering:

12:52:13.849 INFO    nautobot.graphql.schema schema.py                 generate_query_mixin() :
  Beginning generation of Nautobot GraphQL schema
12:52:13.849 DEBUG   nautobot.graphql.schema schema.py                 generate_query_mixin() :
  Generating dynamic schemas for all models in the models_features graphql registry
12:52:13.987 DEBUG   nautobot.graphql.schema schema.py                 generate_query_mixin() :
  Adding plugins' statically defined graphql schema types
12:52:13.987 DEBUG   nautobot.graphql.schema schema.py                 generate_query_mixin() :
  Extending all registered schema types with dynamic attributes
12:52:18.915 INFO    nautobot.graphql.schema schema.py                 generate_query_mixin() :
  Generation of Nautobot GraphQL schema complete

We should not need to render the entire GraphQL schema in order to render the REST API schema.