fix: Revert enable strong session protection by default (#24256)

[michael-s-molina]

SUMMARY

This PR reverts #24256 due to problems with the login and Alerts & Reports found during 2.1.1 tests. It's not a complete revert because I preserved most of the documentation added to security.mdx and only reverted the part about SESSION_PROTECTION.

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 #24545 (01ab3cb) into master (7501134) will increase coverage by 0.12%.
The diff coverage is 100.00%.

❗ Current head 01ab3cb differs from pull request most recent head fa8f3fa. Consider uploading reports for the commit fa8f3fa to get more accurate results

@@            Coverage Diff             @@
##           master   #24545      +/-   ##
==========================================
+ Coverage   68.93%   69.05%   +0.12%     
==========================================
  Files        1903     1903              
  Lines       74027    74025       -2     
  Branches     8118     8118              
==========================================
+ Hits        51027    51115      +88     
+ Misses      20889    20799      -90     
  Partials     2111     2111              

Flag	Coverage Δ
hive	53.88% <50.00%> (?)
mysql	79.41% <100.00%> (-0.01%)	⬇️
postgres	79.48% <100.00%> (-0.02%)	⬇️
presto	53.78% <50.00%> (?)
python	83.43% <100.00%> (+0.25%)	⬆️
sqlite	?
unit	54.64% <50.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
...rontend/src/components/DropdownContainer/index.tsx	65.00% <ø> (ø)
...ilters/FilterBar/FilterControls/FilterControls.tsx	69.73% <ø> (ø)
superset/charts/commands/warm_up_cache.py	97.50% <ø> (ø)
superset/config.py	91.95% <ø> (-0.03%)	⬇️
superset/datasets/commands/warm_up_cache.py	100.00% <ø> (ø)
superset/databases/api.py	89.90% <100.00%> (ø)
superset/initialization/__init__.py	91.35% <100.00%> (-0.03%)	⬇️

... and 12 files with indirect coverage changes

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[dpgaspar]

Thank you