Set API timeout from ENV when credentials are specified in ENV

[kobajagi]

Description

Fixes bug with EXOSCALE_API_TIMEOUT being ignored when credentials are specified in ENV.

Checklist

(For exoscale contributors)

• Changelog updated (under Unreleased block)
• Testing

Testing

Before change:

$ EXOSCALE_API_KEY=xxx EXOSCALE_API_SECRET=xxx EXOSCALE_API_TIMEOUT=1 exo c i snapshot create myinstance -z ch-gva-2
 ✔ Creating snapshot of instance "myinstance"... 3m18s
┼───────────────┼────────────────────────────────────────┼
│   SNAPSHOT    │                                        │
┼───────────────┼────────────────────────────────────────┼
│ ID            │ b41413b9-58bc-4ccf-a498-7391bb603b91   │
│ Name          │ myinstance_ROOT-7380078_20240805161855 │
│ Creation Date │ 2024-08-05 16:18:55 +0000 UTC          │
│ State         │ exported                               │
│ Size (GB)     │ 50                                     │
│ Instance      │ myinstance                             │
│ Zone          │ ch-gva-2                               │
┼───────────────┼────────────────────────────────────────┼

After change:

$ EXOSCALE_API_KEY=xxx EXOSCALE_API_SECRET=xxx EXOSCALE_API_TIMEOUT=1 go run . c i snapshot create myinstance -z ch-gva-2
 ✔ Creating snapshot of instance "myinstance"... 1m0s
error: request timeout reached. Snapshot creation is not canceled and might still be running, check the status with: exo c i snapshot list
exit status 1