VcsCommand: Don't run in separate thread

Change-Id: Ief0e859d3ce48f804e128cc0f5cb1b390a066923
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/vcsbase/vcsplugin.h

@@ -31,7 +31,6 @@ public:
     bool initialize(const QStringList &arguments, QString *errorMessage) override;
 
     static VcsPlugin *instance();
-    static void addFuture(const QFuture<void> &future);
 
     CommonVcsSettings &settings() const;