Use OpenAPI schemas from stacks-blockchain repo

[zone117x]

This PR stacks-network/stacks-core#2459 added OpenAPI schemas to the stacks-blockchain repo for all the /v2 endpoints that this repo proxies to.

The /v2 schemas in this repo are now redundant and will likely become stale, they should be removed, and the doc generation in this repo should pull in the schemas from the stacks-blockchain repo.

Note: this does not include the BNS related /v2 schemas that are not proxied to the stacks-node.