ci: skip unnecessary test steps

[villebro]

SUMMARY

There are two instances where we install Node and Python even if we can skip these tests. This should marginally speed up CI by avoiding unnecessary installation steps.

BEFORE

An example of Node being installed on a backend PR despite not needing to be installed (3 extra seconds):

Same for Python linting (no noticeable change in installation time, but still unnecessary):

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #17005 (87a5741) into master (1cd0124) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #17005      +/-   ##
==========================================
- Coverage   76.92%   76.85%   -0.08%     
==========================================
  Files        1030     1030              
  Lines       55022    55035      +13     
  Branches     7465     7465              
==========================================
- Hits        42328    42298      -30     
- Misses      12440    12488      +48     
+ Partials      254      249       -5     

Flag	Coverage Δ
hive	81.45% <ø> (+<0.01%)	⬆️
javascript	70.90% <ø> (-0.01%)	⬇️
mysql	81.90% <ø> (+<0.01%)	⬆️
postgres	81.91% <ø> (+<0.01%)	⬆️
presto	?
python	82.26% <ø> (-0.14%)	⬇️
sqlite	81.58% <ø> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
superset/db_engine_specs/presto.py	84.30% <0.00%> (-5.65%)	⬇️
superset/connectors/sqla/models.py	85.83% <0.00%> (-1.42%)	⬇️
superset/models/core.py	89.26% <0.00%> (-0.74%)	⬇️
...frontend/src/SqlLab/components/ResultSet/index.tsx	61.48% <0.00%> (-0.46%)	⬇️
superset/utils/pandas_postprocessing.py	84.42% <0.00%> (ø)
superset-frontend/src/views/CRUD/hooks.ts	47.23% <0.00%> (ø)
superset-frontend/src/views/CRUD/utils.tsx	56.48% <0.00%> (ø)
...perset-frontend/src/views/CRUD/chart/ChartList.tsx	74.35% <0.00%> (ø)
...set-frontend/src/views/CRUD/welcome/ChartTable.tsx	73.17% <0.00%> (ø)
...frontend/src/views/CRUD/welcome/DashboardTable.tsx	64.89% <0.00%> (ø)
... and 6 more

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[zhaoyongjie]

LGTM!

[AAfghahi]

🏷 v1.4