Description of problem:
"Test connection" for a HTTP Proxy ignores proxy password when sending CONNECT request over the wire. This raises false alarms about the proxy setup.

Gladly, syncing a repository via such a HTTP Proxy works fine, it is just a matter of test_connection feature/method.

Checking tcpdump from a communication, an empty password is send, like when testing connection via WebUI:

Hypertext Transfer Protocol
CONNECT aws.amazon.com:443 HTTP/1.1\r\n
Host: aws.amazon.com:443\r\n
<Host: aws.amazon.com:443\r\n>
Proxy-Authorization: Basic cHJveHk6\r\n
Credentials: proxy: <----- see here empty password
<Proxy-Authorization: Basic cHJveHk6\r\n>
\r\n
[Full request URI: aws.amazon.com:443]
<Request: True>
[HTTP request 1/1]
[Response in frame: 10]

foreman-rake itself does work well, though:

irb(main):002:0> HttpProxy.first.password
=> "password"
irb(main):003:0> HttpProxy.first.test_connection("https://aws.amazon.com")
=> <RestClient::Response 200 "">

Version-Release number of selected component (if applicable):
Sat 6.10.4 and also .5

How reproducible:
100%

Steps to Reproduce:
1. Have a HTTP Proxy requiring credentials
2. Configure such HTTP Proxy in Satellite
3. Test connection (ideally while running tcpdump to see what's happening on wire)

Actual results:
3. Fails with 407 "Proxy Authentication Required" error.
tcpdump shows empty password is sent in credentials

Expected results:
3. Test connection to work (again, we feel 6.10.3 worked well but we dont have a proof)
tcpdump showing password is sent to the proxy for auth

Additional info: