remove element path from tinyMCE
remove element path from tinyMCE

fixes CNVS-22184

test plan:
  - go to several pages with tinyMCE
  - none of them have a "p" at
    the bottom (or h1/h2/em/div etc)
  - they work normally

Change-Id: I3e1e517673daa423b9b89e1560faecab435fad31
Reviewed-on: https://gerrit.instructure.com/59405
Product-Review: Cosme Salazar <d37f5e06cd46b8fd23ce5553334e09ede5394232@instructure.com>
Tested-by: Jenkins
Reviewed-by: Ethan Vizitei <73eeb0b2f65d05a906adf3b21ee1f9f5a2aa3c1c@instructure.com>
QA-Review: August Thornton <9adc7a1161ddf32ff608de792a7e50179545f026@instructure.com>

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