Add project key to cache key

[thomas-boehm-tractive]

If a requests is sent with a project key, and the key is not part of the cache key, following requests for other projects will result in the cached repositories for the first project, leading to wrong results

Your checklist for this pull request

• [x] Make sure you are requesting to pull a topic/feature/bugfix branch (right side) and not your master branch!
• [x] Ensure that the pull request title represents the desired changelog entry
• [x] Please describe what you did
• [x] Link to relevant issues in GitHub or in Jenkins JIRA
• [x] Link to relevant pull requests, esp. upstream and downstream changes
• [ ] Did you provide a test-case? That demonstrates feature works or fixes the issue.
  • No, as I don't know how to write such a test case.

Fixes #836

[thomas-boehm-tractive]

@KalleOlaviNiemitalo @lifeofguenter does anything speak against merging this PR? I think this is a very useful bugfix, as caching without the project key causes issues.

[nfalco79]

@KalleOlaviNiemitalo any update on this?

[nfalco79]

i hope that at least one of the current maintainer will take action on this PR @dwnusbaum @bitwiseman @car-roll This PR was already reviewed and stucks here from a very long time.

@lifeofguenter this is not a feature but a bug fix. Because cache feature was already in place. Using the BB project key in the organization folder configuration is ignore on project rescan causing on this folder to be populated with all repositories regardless in which project they are.

[nfalco79]

Could you @thomas-boehm-tractive perform rebase from master?

[thomas-boehm-tractive]

@nfalco79 rebased onto master, as requested here: https://github.com/jenkinsci/bitbucket-branch-source-plugin/pull/837#issuecomment-2443645719