COMP: restore waitForImportFinished API (no-op) for dicom indexer

See:
https://github.com/commontk/CTK/commit/ac7cf1665a8c8581998476a11778f78dfcedc4d9

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21664 3bd1e089-480b-0410-8dfb-8563597acbee