Description of problem:
Repo discovery via HTTP proxy defined by IPv6 address doesn't work

How reproducible:
deterministic
 

Is this issue a regression from an earlier version:
no
 

Steps to Reproduce:

1. Create HTTP proxy using its IPv6 address in URL and set it as the default proxy for content

Infrastructure -> HTTP proxies -> [ New HTTP proxy ]

URL* [ http://[<IPv6_ADRESS>]:3128 ]
Default content HTTP proxy [yes]

2. Try to perform repository discovery

Content -> Products -> [ Repo Discovery ]

Repository Type [ Yum Repositories / Container Images ]
URL to Discover [ http://infra-podman-ipv6.example.com:50123/repo_discovery ]
or
Registry to Discover [ quay.io ]

>> No repository or image discovered, for yum repos an exception is swallowed, while for container images it is shown:

(!) Error
Discovery failed. Error: bad URI(is not URI?): 
"proxy://xxxx:xx:x:xx:xxxx:xxxx:xxxx:xxxx:3128"

Actual behavior:
[Describe the issue in detail, including what is happening and where]
No repository or image discovered

Expected behavior:
[Describe what should be happening instead]
Yum repositories and container images are discovered

Business Impact / Additional info:
Continuation of SAT-24175