9463: Using finally: on except: clause to stop the updater thread on error or finishe...

9463: Using finally: on except: clause to stop the updater thread on error or finished work. When counting the collection size, stopped ignoring items that are not Collection or ArvadosFile, in case some other class is used in the future. When getting block locators (for example when called with --raw), don\'t make sure the blocks are flushed to Keep before asking for segments