bbb-tool: Removed file that caused the build to break

bbb-lti/grails-app/assets/stylesheets/tool.css

-/*
-* This is a manifest file that'll be compiled into application.css, which will include all the files
-* listed below.
-*
-* Any CSS file within this directory can be referenced here using a relative path.
-*
-* You're free to add application-wide styles to this file and they'll appear at the top of the
-* compiled file, but it's generally better to create a new file per style scope.
-*
-*= require_self
-*/