Replace WaitForFinishedInParentDirectory with WaitForFinished for directory moves

Replace WaitForFinishedInParentDirectory with WaitForFinished for directory moves

In preparation for the PropagateDirectory refactoring, simplify things
by removing WaitForFinishedInParentDirectory, which is currently
implemented as a one-level check.

This value is important for directory items, but is however never
used since a directory CSYNC_INSTRUCTION_RENAME item will always be in
PropagateDirectory::_firstJob, which will have to pass through its own
PropagateDirectory job's parallelism() before reaching the parent's
_subJobs optimization.
Since PropagateDirectory::parallelism can only return WaitForFinished
or FullParallelism, that value is lost. So this commit doesn't
change the behavior for directories, and allow file renames to be
scheduled in parallel across directories (which isn't a problem).