ECMS-6407: NPE and redundant comment after adding 1 webcontent in CLV

Problem analysis
- When a file is created in taxonomy folder, it is moved to web content and a symlink targeting to this node in taxonomy folder.
- During the progress above, when the moved file's property is changed, the event "update content" is triggered because the only new file in taxonomy folder is marked as creating.

Fix description
- Mark original file as creating if at least one of its symlink is in the creating list