chore: remove markup and separator from viz.py

[villebro]

SUMMARY

The markup and separator viz shims are no longer needed in viz.py.

TEST PLAN

CI

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[codecov-commenter]

Codecov Report

Merging #9997 into master will increase coverage by 4.85%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #9997      +/-   ##
==========================================
+ Coverage   65.58%   70.43%   +4.85%     
==========================================
  Files         585      585              
  Lines       31020    30986      -34     
  Branches     3277     3277              
==========================================
+ Hits        20345    21826    +1481     
+ Misses      10494     9048    -1446     
+ Partials      181      112      -69     

Flag	Coverage Δ
#cypress	53.90% <ø> (?)
#javascript	59.37% <ø> (ø)
#python	70.05% <ø> (+0.07%)	⬆️

Impacted Files	Coverage Δ
superset/viz.py	57.13% <ø> (-0.02%)	⬇️
superset/viz_sip38.py	0.00% <ø> (ø)
...rontend/src/SqlLab/components/AceEditorWrapper.tsx	56.98% <0.00%> (+1.07%)	⬆️
superset-frontend/src/components/EditableTitle.jsx	81.69% <0.00%> (+1.40%)	⬆️
...perset-frontend/src/components/CopyToClipboard.jsx	36.36% <0.00%> (+1.51%)	⬆️
...hboard/components/resizable/ResizableContainer.jsx	71.87% <0.00%> (+1.56%)	⬆️
...ashboard/components/gridComponents/ChartHolder.jsx	81.35% <0.00%> (+1.69%)	⬆️
superset-frontend/src/utils/common.js	69.64% <0.00%> (+1.78%)	⬆️
...src/explore/components/controls/VizTypeControl.jsx	78.84% <0.00%> (+1.92%)	⬆️
superset-frontend/src/explore/controlUtils.js	96.90% <0.00%> (+2.06%)	⬆️
... and 140 more

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