could not use with couchbase:// scheme on custom port

cbdinocluster sets up alternate ports (running in docker) and I set up my config to use the supplied connstr. Unfortunately, it didn't work.

```
➜ couchbase-shell git:(main) ✗ target/debug/cbsh
[WARN] 2024-07-18 12:44:00.659 Using PLAIN authentication for cluster mbp, credentials will sent in plaintext - configure tls to disable this warning
[ERROR] 2024-07-18 12:44:00.659 Couchbase scheme and non-default port detected, http scheme must be used with custom port (management port)
```
Unfortunately, this is validated at startup, so I couldn't use shell at all even though other configs were valid. Maybe we should validate them at the time of loading a particular environment?

I removed the validation, and that let me start the process. A later failure happened when doing an upsert:

Failed to load cluster config: │ ... │
│ │ │ │ │ error sending request for url (http │ │
│ │ │ │ │ ://192.168.106.3:30433/pools/defaul │ │
│ │ │ │ │ t/b/acm)

So it looks like we need some enhancement to support doing enough bootstrap to get config or get HTTP for retrieving config.

Begin at the startup validation for the Couchbase scheme and custom-port check, then trace the upsert path that loads cluster config and retrieves HTTP. Done means a valid custom-port configuration can start and successfully bootstrap cluster config for an upsert without producing an invalid management URL.

Written by the indexing model from the issue text.