cubicweb-medicalexp #3446603 [schema] Study.data_filepath: shoud not be indexed and maxsize too small [validation pending]

We have noticed that Study.data_filepath is indexed: this does not seem useful.
We have also found that maxsize=1024 might not be sufficient.

The same holds for:
Configuration.filepath
GenericMeasure.filepath
ExternalResource.filepath

While discussing this with Vincent, it appeared they should be removved

prioritynormal
typeenhancement
done in0.9.0
load0.200
load left0.000
closed by<not specified>