TrainGMMApp (strange name) fails with qgisdescriptor
### Description
Dashboard is failing
```
./bin/otbQgisDescriptor TrainGMMApp ./lib/otb/applications ./share/otb/description/
C:\dashboard\otb\superbuild_x64\OTB\build\bin\otbQgisDescriptor.exe TrainGMMApp C:/dashboard/otb/superbuild_x64/OTB/build/lib/otb/applications C:/dashboard/otb/superbuild_x64/OTB/build/share/otb/description/
```
ERROR: default_value is empty for 'sample.edg' type='QgsProcessingParameterBoolean'
### Steps to reproduce
`./bin/otbQgisDescriptor TrainGMMApp ./lib/otb/applications ./share/otb/description/`
### Configuration information
https://dash.orfeo-toolbox.org/viewBuildError.php?buildid=318336
issue