refactor: sql_json view endpoint: extract to method for code reusing

[ofekisr]

SUMMARY
The sql_json view code in superset core view without any "clean code" standard and it does not adopt any software development principle.
This is the third PR in the sequence of future PRs (previous PR) try to solve it by refactoring the code.
The PR focus of extract to a method for code reusing
TESTING INSTRUCTIONS
there are no logic changes so it implies on the current tests.

[codecov]

Codecov Report

Merging #16546 (819cf56) into master (80c39da) will decrease coverage by 0.13%.
The diff coverage is 100.00%.

❗ Current head 819cf56 differs from pull request most recent head 2b8c67f. Consider uploading reports for the commit 2b8c67f to get more accurate results

@@            Coverage Diff             @@
##           master   #16546      +/-   ##
==========================================
- Coverage   76.72%   76.58%   -0.14%     
==========================================
  Files        1002     1002              
  Lines       53798    53801       +3     
  Branches     6858     6858              
==========================================
- Hits        41274    41202      -72     
- Misses      12287    12362      +75     
  Partials      237      237              

Flag	Coverage Δ
hive	?
mysql	81.54% <100.00%> (+<0.01%)	⬆️
postgres	81.57% <100.00%> (+<0.01%)	⬆️
presto	81.37% <100.00%> (-0.04%)	⬇️
python	81.80% <100.00%> (-0.27%)	⬇️
sqlite	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/views/core.py	75.59% <100.00%> (+0.05%)	⬆️
superset/db_engines/hive.py	0.00% <0.00%> (-82.15%)	⬇️
superset/db_engine_specs/hive.py	69.80% <0.00%> (-16.87%)	⬇️
superset/db_engine_specs/sqlite.py	91.89% <0.00%> (-5.41%)	⬇️
superset/connectors/sqla/utils.py	88.23% <0.00%> (-3.93%)	⬇️
superset/utils/celery.py	86.20% <0.00%> (-3.45%)	⬇️
superset/result_set.py	96.77% <0.00%> (-1.62%)	⬇️
superset/utils/cache.py	73.58% <0.00%> (-0.95%)	⬇️
superset/connectors/sqla/models.py	89.46% <0.00%> (-0.24%)	⬇️
superset/utils/core.py	89.76% <0.00%> (-0.13%)	⬇️
... and 1 more

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[amitmiran137]

Clear method extraction.
LGTM!

[junlincc]

is there any risks that we should be aware of from those refactoring PRs?