Remove commons-httpclient3-api plugin

[strangelookingnerd]

Remove the deprecated / outdated httpclient3-api plugin. On further investigation, httpclient3 is not required in the first place.

Testing done

Validated via mvn verify

### Submitter checklist
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- [x] Ensure that the pull request title represents the desired changelog entry
- [x] Please describe what you did
- [ ] Link to relevant issues in GitHub or Jira
- [ ] Link to relevant pull requests, esp. upstream and downstream changes
- [x] Ensure you have provided tests - that demonstrates feature works or fixes the issue