Test Python clients in CircleCI

[wing328]

Move python client tests to CircleCI due to low credits in other CI.

cc @spacether

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.
• File the PR against the correct branch: master (5.3.0), 6.0.x
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @taxpon (2017/07) @frol (2017/07) @mbohlool (2017/07) @cbornet (2017/09) @kenjones-cisco (2017/11) @tomplus (2018/10) @Jyhess (2019/01) @arun-nalla (2019/11) @spacether (2019/11)

[wing328]

Travis, Appveyor failure not related to this change.

[spacether]

Should the other circleci samples be renamed as node1, node2 etc rather than misc?
Or maybe something like node2_javasampleses

[wing328]

Will do it in another PR instead. So many things need to be cleanup in the CI 😭

[spacether]

Thanks for the pr! This looks good. Do you want me to merge it or do you want to?

[wing328]

Just merged.