remove zip_file_import attachments after table is dropped
remove zip_file_import attachments after table is dropped

fixes foreign key problems

Change-Id: Icdfc445c2ca08b1fd3342d37217771294768dbf9
Reviewed-on: https://gerrit.instructure.com/77837
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Tested-by: Jenkins
Product-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
QA-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>

djbender/canvas-lms,grahamb/canvas-lms,roxolan/canvas-lms,HotChalk/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,grahamb/canvas-lms,fronteerio/canvas-lms,djbender/canvas-lms,SwinburneOnline/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,HotChalk/canvas-lms,roxolan/canvas-lms,djbender/canvas-lms,HotChalk/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,fronteerio/canvas-lms,SwinburneOnline/canvas-lms,grahamb/canvas-lms,roxolan/canvas-lms,fronteerio/canvas-lms,grahamb/canvas-lms,roxolan/canvas-lms,SwinburneOnline/canvas-lms,sfu/canvas-lms,SwinburneOnline/canvas-lms,HotChalk/canvas-lms,venturehive/canvas-lms,venturehive/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,fronteerio/canvas-lms