DownloadManager - remove unnecessary done() call on ProgressMonitor

[vogella]

See https://www.eclipse.org/articles/Article-Progress-Monitors/article.html

[github-actions]

Test Results

  375 files  ±0    375 suites  ±0   44m 3s ⏱️ - 1m 16s
1 904 tests ±0  1 901 ✅ ±0  3 💤 ±0  0 ❌ ±0 
6 712 runs  ±0  6 703 ✅ ±0  9 💤 ±0  0 ❌ ±0 

Results for commit 71c67fa. ± Comparison against base commit 1a42e02.

♻️ This comment has been updated with latest results.

[vogella]

@ptziegler a full text search shows tons of .done() in the repo.

Can you have a quick look at this trivial change?

[ptziegler]

This method already has a SubMonitor, which explicitly says that done() doesn't need to be called. So that looks fine to me.

[vogella]

Thanks @ptziegler