Fix #2559: Remove obsolete virtualenv and legacy errors from FAQ

[zer-art]

Fixes #2559

Changes Proposed:

This PR removes legacy FAQ sections that instructed users to use virtualenv, install system-level dependencies (like libpq-dev), and use Python 2.7. These instructions are incompatible with the current Docker-based workflow.

I applied these fixes to both the active documentation and the legacy file to ensure consistency:

1. docs/source/07-troubleshooting/support/faq.md (Active Docs)
2. docs/source/faq(developers).md (Legacy/Direct Link)

Specific removals:

• Removed "Logs & Debugging" section (referenced obsolete psycopg2 host-side fixes).
• Removed "Common Node, npm & Frontend Issues" (referenced global host-side installs).
• Removed "Proxy / Network Issues" (referenced local npm config).
• Updated "Python & Backend Errors" to remove the legacy Python 2.7 recommendation.

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 91.90%. Comparing base (d4ce4fa) to head (61f829e).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4817      +/-   ##
==========================================
+ Coverage   91.89%   91.90%   +0.01%     
==========================================
  Files          86       86              
  Lines        7132     7132              
==========================================
+ Hits         6554     6555       +1     
+ Misses        578      577       -1     

Flag	Coverage Δ
backend	96.67% <ø> (ø)
frontend	87.17% <ø> (+0.02%)	:arrow_up:

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

Components	Coverage Δ
Accounts & Authentication	100.00% <ø> (ø)
Challenges Management	95.39% <ø> (ø)
Job Processing	98.19% <ø> (ø)
Participants & Teams	100.00% <ø> (ø)
Challenge Hosts	100.00% <ø> (ø)
Analytics	100.00% <ø> (ø)
Web Interface	100.00% <ø> (ø)
Frontend (Gulp)	87.17% <ø> (+0.02%)	:arrow_up:
All Models	97.58% <ø> (ø)
All Views	100.00% <ø> (ø)
All Serializers	98.82% <ø> (ø)
Utility Functions	96.82% <ø> (ø)
Core Configuration	82.35% <ø> (ø)
see 1 file with indirect coverage changes
see 1 file with indirect coverage changes

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