improve scene release sequence

[summeroff]

Description

Motivation and Context

fix will make scene to be removed before scene items. it is safer as other threads might still work with a scene in a middle of scene item removal.
call scene item remove before scene item release.

How Has This Been Tested?

custom build tested by people who reproduced issue before.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.