Deleting a process is inefficient

[matthias-ronge]

When you delete a process, the script_removeSymLink runs for each task, for each role assigned to the task, for each user assigned to the role (see ProcessService). This is highly inefficient because shell calls are expensive (especially on Windows). The link is not removed for users who are not related to the process via a task (but have used the button to link processes to the home directory).

Goal: The best solution would be to have a separate script that searches for and removes corresponding symbolic links in all user directories. At least, the script should not be called more than once per user. This could happen separately for all users in the background in the task manager.

[matthias-ronge]

Script also suggested in #3258

[matthias-ronge]

This means not only adding the possibility for a script, and writing a sample script, but it also means removing the Java code that did the deleting before.