[docs] remove src lines. All tutorials should show all lines

[odow]

Part of #4124. We don't need to execute the tutorials twice and hide some of the test lines.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.91%. Comparing base (0b42e5f) to head (4ad596c).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4126   +/-   ##
=======================================
  Coverage   99.91%   99.91%           
=======================================
  Files          42       42           
  Lines        6224     6224           
=======================================
  Hits         6219     6219           
  Misses          5        5           

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