build(target-platform): Remove obsolete .gitignore file
build(target-platform): Remove obsolete .gitignore file

Target platform definition files are no longer generated locally, so all
file changes should be considered to be committed in project
"target-platform".
b2ihealthcare/snow-owl,b2ihealthcare/snow-owl,b2ihealthcare/snow-owl,b2ihealthcare/snow-owl