Monkey patch Net::HTTP proxy encoding

What does this MR do?

It monkey patches Net::HTTP to fix #289836 (closed).

When using a proxy with authentication, and the user or password contain special characters, credentials will be URL encoded. The example in #289836 (closed) shows a proxy with username YYYYY\XXXX and password: RBr%S]axMD-F1S? resulting in a proxy setting of http://YYYYY%5CXXXX:RBr%25S%5DaxMD-F1S%3F@127.0.0.1:3128.

Net::HTTP uses those credentials to create a Base64 encoded auth header but it does not decode the values first.

There is an upstream fix from @leipert for this but until it get's accepted we want to monkey patch Net::HTTP.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done