Shorten the running time of gprecoverseg related test cases

Commit a2c3dd20 unexpectly cause test_fts_transitions_02 running
for a longer time, so revert related modification from it.

src/test/tinc/tincrepo/mpp/lib/gprecoverseg.py

@@ -43,8 +43,6 @@ class GpRecoverseg():
 
         pool = WorkerPool()
         pool.addCommand(cmd)
-        pool.join()
-        pool.haltWork()
 
     def run(self,option=' ', validate=True, results=True):
         '''