fix calendar event color reverting to previous color on hover
fix calendar event color reverting to previous color on hover

test plan:
 - ensure that, after changing the color for a course's events
   on the calendar and before refreshing the page, that the
   events don't revert to their old color while hovering over them

fixes CNVS-28621

Change-Id: Id989017ded050ca793b0401540374c195604fcc1
Reviewed-on: https://gerrit.instructure.com/77276
Tested-by: Jenkins
Reviewed-by: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
QA-Review: Deepeeca Soundarrajan <5bcd4b623f00b7fc2942cd1c65c245b30a48a61f@instructure.com>
Product-Review: Jeremy Stanley <b3f594e10a9edcf5413cf1190121d45078c62290@instructure.com>

HotChalk/canvas-lms,fronteerio/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,matematikk-mooc/canvas-lms,fronteerio/canvas-lms,instructure/canvas-lms,HotChalk/canvas-lms,grahamb/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,SwinburneOnline/canvas-lms,SwinburneOnline/canvas-lms,roxolan/canvas-lms,instructure/canvas-lms,dgynn/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,dgynn/canvas-lms,venturehive/canvas-lms,dgynn/canvas-lms,dgynn/canvas-lms,grahamb/canvas-lms,SwinburneOnline/canvas-lms,sfu/canvas-lms,matematikk-mooc/canvas-lms,SwinburneOnline/canvas-lms,HotChalk/canvas-lms,matematikk-mooc/canvas-lms,djbender/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,HotChalk/canvas-lms,roxolan/canvas-lms,instructure/canvas-lms,matematikk-mooc/canvas-lms,roxolan/canvas-lms,fronteerio/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,fronteerio/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,roxolan/canvas-lms