don't fail if trigger doesn't exist
don't fail if trigger doesn't exist

Change-Id: Icbf113c4d62a8ead8f0ad8631f7c2f05c5bdea8f
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/273721
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Reviewed-by: Dustin Cowles <25afa0fec7fcf03720748195b533ef56026fd0cf@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Tested-by: Aaron Ogata <11ccf682c06d1508642f943a3962a1c3d00b8e44@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms