test(python): Add tests for data mismatch on read_json

[nameexhaustion]

Add some explicit tests for read_json - the underlying code was already fixed by #19347 as it is shared with str.json_decode

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.03%. Comparing base (69c9c3a) to head (48d17d0).
Report is 36 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #19425   +/-   ##
=======================================
  Coverage   80.03%   80.03%           
=======================================
  Files        1532     1532           
  Lines      210749   210749           
  Branches     2442     2442           
=======================================
+ Hits       168676   168677    +1     
+ Misses      41518    41517    -1     
  Partials      555      555           

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