Description of problem:
When creating new HTTP Proxy, the `Test Connection` returns a `Success alert:HTTP Proxy connection successful.`, even when the URL entered is invalid.

Version-Release number of selected component (if applicable):
Satellite 6.13.0 Snap 13

How reproducible:
Always

Steps to Reproduce:
1. Go to Satellite -> Infrastructure -> HTTP Proxies
2. New HTTP Proxy
3. Enter an invalid URL in URL field
4. Click `Test Connection`

Actual results:
`Success alert:HTTP Proxy connection successful.` returned always even with invalid URL.

Expected results:
Success alert only for valid URLs, error alert for invalid URLs.