remove support for non-prefixed env vars

[frascuchon]

Description

This PR removes support for non-prefixed environment variables. All used env vars should start with ARGILLA_. This change also fixes a problem with the elastic replica set configuration if the primary shard configuration is modified.

Type of change

(Please delete options that are not relevant. Remember to title the PR according to the type of change)

• Bug fix (non-breaking change which fixes an issue)
• Improvement (change adding some improvement to an existing functionality)

Checklist

• I added relevant documentation
• follows the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[codecov]

Codecov Report

Patch coverage: 94.67% and project coverage change: +0.37 🎉

Comparison is base (6630d7b) 90.13% compared to head (36129bf) 90.51%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3392      +/-   ##
===========================================
+ Coverage    90.13%   90.51%   +0.37%     
===========================================
  Files          233      242       +9     
  Lines        12493    12930     +437     
===========================================
+ Hits         11261    11703     +442     
+ Misses        1232     1227       -5     

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Impacted Files	Coverage Δ
...ack/integrations/huggingface/card/_dataset_card.py	100.00% <ø> (ø)
.../feedback/integrations/huggingface/card/_parser.py	100.00% <ø> (ø)
src/argilla/feedback/__init__.py	100.00% <ø> (ø)
src/argilla/tasks/database/migrate.py	39.13% <ø> (-4.87%)	⬇️
src/argilla/training/autotrain_advanced.py	0.00% <0.00%> (ø)
src/argilla/utils/telemetry.py	89.09% <ø> (ø)
src/argilla/server/settings.py	77.41% <50.00%> (-3.76%)	⬇️
src/argilla/server/database.py	75.00% <63.63%> (-25.00%)	⬇️
...lient/feedback/integrations/huggingface/dataset.py	86.80% <86.80%> (ø)
src/argilla/client/feedback/dataset.py	79.86% <90.00%> (-2.36%)	⬇️
... and 63 more

... and 7 files with indirect coverage changes

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