Improve consul secrets plugin error for failed bootstrap

[tomhjp]

When returning a logical error, we need to include all of the information the user should see within the response. As seen in #18705, there is currently no indication of why the bootstrapping failed when it does.

Before:

$ vault write consul/config/access \
    address="https://127.0.0.1:8500"
Error writing data to consul/config/access: Error making API request.

URL: PUT http:https://127.0.0.1:8200/v1/consul/config/access
Code: 400. Errors:

* Token not provided and failed to bootstrap ACLs

After:

$ vault write consul/config/access \
    address="https://127.0.0.1:8500"
Error writing data to consul/config/access: Error making API request.

URL: PUT http:https://127.0.0.1:8200/v1/consul/config/access
Code: 400. Errors:

* Token not provided and failed to bootstrap ACLs: Put "https://127.0.0.1:8500/v1/acl/bootstrap": http: server gave HTTP response to HTTPS client