Prevent precise timers from being used when unnecessary

The implementation of QTimer::singleShot() uses Qt::PreciseTimer if interval is less than 2 seconds. This isn't mentioned in the docs.
Qt::PreciseTimer increases the system's timer resolution which negatively affects power consumption.

PR #18555.
Closes #18350.

src/base/torrentfileswatcher.cpp

@@ -502,7 +502,7 @@ void TorrentFilesWatcher::Worker::removeWatchedFolder(const Path &path)
 
 void TorrentFilesWatcher::Worker::scheduleWatchedFolderProcessing(const Path &path)
 {
-    QTimer::singleShot(2s, this, [this, path]()
+    QTimer::singleShot(2s, Qt::CoarseTimer, this, [this, path]
     {
         processWatchedFolder(path);
     });