:bug: Firewalled/proxy environment difficulties

**Describe the bug**

We have an environment where outbound access is firewalled and HTTP(s) access goes through a proxy. After following the (disappointing, but somewhat understandble) discussions on this topic in e.g. #350, I requested exemptions as per the document here:

https://developers.cloudflare.com/cloudflare-one/connections/connect-networks/deploy-tunnels/tunnel-with-firewall/

However, it appears these are still insufficient - a hello world test still doesn't work.

**To Reproduce**
Steps to reproduce the behavior:

```
# https_proxy=redacted ./cloudflared-linux-amd64 tunnel --hello-world
2024-05-06T02:42:28Z INF Thank you for trying Cloudflare Tunnel. Doing so, without a Cloudflare account, is a quick way to experiment and try it out. However, be aware that these account-less Tunnels have no uptime guarantee. If you intend to use Tunnels in production you should use a pre-created named tunnel by following: https://developers.cloudflare.com/cloudflare-one/connections/connect-apps
2024-05-06T02:42:28Z INF Requesting new quick Tunnel on trycloudflare.com...
... hangs ...
```

And using strace I can see it is trying to connect directly to `api.trycloudflare.com`, not using a proxy:

```
[pid 29248] connect(3, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("104.16.231.132")}, 16) = -1 EINPROGRESS (Operation now in progress)
[pid 29249] connect(3, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("104.16.230.132")}, 16) = -1 EINPROGRESS (Operation now in progress)
```

**Expected behavior**

I'd really have hoped the conventional HTTP(S) API calls required to setup the tunnels should be able to be made through a proxy. I've seen justifications elsewhere for the tunnel itself to not support proxied operation due to a preference for QUIC, and while that's disappointing it's at least understandable from a technical standpoint. The non-tunnel setup operations should still be proxyable though.

The page above listing required firewall exemptions potentially also needs amending to list `api.trycloudflare.com` for quick tunnels.

**Environment and versions**
- OS: Linux
- Architecture: AMD64
- Version: 2024.4.1

**Logs and errors**

See above.

**Additional context**
Add any other context about the problem here.