Fix findPluginsToDownload falsely check installed version

[anhcraft]

I noticed that PluginManager#findPluginsToDownload has a wrong logic if-else. For a requested plugin, if there is both installed plugin and bundled plugin, then the method only gets the version from the installed one without checking if the bundled one is newer. The else logic was added in c445dea

Testing done

I have adjusted the test case to suit the new changes.

Submitter checklist

Tasks

Beta Give feedback

1. Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
2. Ensure that the pull request title represents the desired changelog entry
3. Please describe what you did
4. Link to relevant issues in GitHub or Jira
5. Link to relevant pull requests, esp. upstream and downstream changes
6. Ensure you have provided tests - that demonstrates feature works or fixes the issue