Set proxy in ruby faraday client if configured

[sled]

This PR relates to the bug reported in #14596 and configures the proxy for the Ruby Faraday client if a proxy is configured. It also adds a spec to ensure the proxy is set properly.

@cliffano @zlx @autopp

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  For Windows users, please run the script in Git BASH.
• In case you are adding a new generator, run the following additional script :

  ./bin/utils/ensure-up-to-date.sh
  

  Commit all changed files.
• File the PR against the correct branch: master (6.3.0) (minor release - breaking changes with fallbacks), 7.0.x (breaking changes without fallbacks)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

[sled]

Specs now running properly:

.......................

Finished in 0.01526 seconds (files took 0.25492 seconds to load)
23 examples, 0 failures

[wing328]

thanks for the PR. can you please follow step 3 to update the samples so that the CI can verify the change?

[sled]

@wing328 thanks for the hint, looks like I ran into some problem with Java yesterday and didn't notice the error. Running it in docker did the trick.

[wing328]

@sled thanks for the PR, which has been merged.