Description of problem:

Syncing repositories with https proxy set ends with warning Katello::Errors::Pulp3 Error Only http proxies are supported

Version-Release number of selected component (if applicable):

6.10

How reproducible:

100

Steps to Reproduce:
1. Create HTTP proxy with HTTPS URL
2. Set the Default HTTP Proxy for syncing content from setting to the created one.
3. Sync any Red Hat repository.

Actual results:

The syncing task finishes with warning with the following message :

Katello::Errors::Pulp3Error

Only http proxies are supported

Expected results:

Both HTTP and HTTPS proxies should work without issues.

Additional info:

• Changing the proxy URL from https to http works.
• No hints to use only http proxy.
• The example URL of the URL section when creating a proxy contains https example "URL of the proxy including schema (https://proxy.example.com:8080)"