Set FA instead of b0 as default map for HCP

[arokem]

Despite the fact that this is reordered:

tractoscope/public/datasetConfig.json

Lines 321 to 327 in 14f61c9

	"model-DKI_FA",
	"b0",
	"model-CSD_APM",
	"model-DKI_AWF",
	"model-DKI_MD",
	"model-DKI_MK",
	"model-DTI_FA"

We still get b0 as the default background map. I wonder whether string sorting order is imposed as some point.