Use allowed_xblocks settings (#27265)
Use allowed_xblocks settings (#27265)

* Use allowed_xblocks in olxcleaner validate. 
eduNEXT/edx-platform,arbrandes/edx-platform,arbrandes/edx-platform,arbrandes/edx-platform,eduNEXT/edunext-platform,eduNEXT/edunext-platform,EDUlib/edx-platform,edx/edx-platform,edx/edx-platform,angelapper/edx-platform,edx/edx-platform,angelapper/edx-platform,eduNEXT/edx-platform,eduNEXT/edunext-platform,EDUlib/edx-platform,eduNEXT/edx-platform,angelapper/edx-platform,edx/edx-platform,EDUlib/edx-platform,angelapper/edx-platform,eduNEXT/edunext-platform,EDUlib/edx-platform,arbrandes/edx-platform,eduNEXT/edx-platform