spec: stabilize groups_teacher_spec
spec: stabilize groups_teacher_spec

refs CNVS-25916

this spec fails reliably when not all the events have re-bound
yet after switching the leader position of the student.  Adding
a normal ajaximations reliably solves the fragility in local
and jenkins node tests.

TEST PLAN:
 1) groups_teacher_spec:167 should stop being the most common
    fragile spec

Change-Id: I68d39a0566b183d3fb81c6eded599145fda9fc67
Reviewed-on: https://gerrit.instructure.com/70901
Reviewed-by: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
Tested-by: Jenkins
Product-Review: Ethan Vizitei <73eeb0b2f65d05a906adf3b21ee1f9f5a2aa3c1c@instructure.com>
QA-Review: Ethan Vizitei <73eeb0b2f65d05a906adf3b21ee1f9f5a2aa3c1c@instructure.com>

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