Check filepath= generation, especially for PFSC*00.fits files; drop centroids HDU

It looks like the gen2Actor is getting the filename key for the PFSC*00.fits files before the fits file is closed, and so archiving fails. In fact, the filename= key might be generated twice. Rationalize this and make sure the FITS file is closed before generating the key.

And at some point we agreed to stop appending the centroids HDU to the PFSC files. Doing that will probably help with the other issue.