Fix GB history search form tab order
Fix GB history search form tab order

fixes EVAL-1262
flag=final_grade_override_in_gradebook_history

Test plan:
- Smoke test the Gradebook History page to make sure searching and
  filters still work as expected
- Using VoiceOver or other KVO software, tab through the search form and
  check that all the elements on the left (including the checkbox)
  precede the "Filter" button
  - Check this with the "Final Grade Override in Gradebook History"
    feature flag both enabled and disabled

Change-Id: I3f29fb8932e544d4d09971527fe2b5234d2571fd
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/249985
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Gary Mei <4dff5ebcff9ed76793b70b9470ac64791a16ed11@instructure.com>
Reviewed-by: Syed Hussain <1379c89cd1d253d3c5a299cc4d8f6002ada9d6b5@instructure.com>
QA-Review: Syed Hussain <1379c89cd1d253d3c5a299cc4d8f6002ada9d6b5@instructure.com>
Product-Review: Syed Hussain <1379c89cd1d253d3c5a299cc4d8f6002ada9d6b5@instructure.com>

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