[PM-37042] chore: Add eu.weblibre.gecko.alpha to privileged apps

[FaFre]

Follow up of #6299 to support alpha builds eu.weblibre.gecko.alpha signatures identical to main release of eu.weblibre.gecko

[bitwarden-bot]

Thank you for your contribution! We've added this to our internal Community PR board for review.
ID: PM-37042
Link: https://bitwarden.atlassian.net/browse/PM-37042

Details on our contribution process can be found here: https://contributing.bitwarden.com/contributing/pull-requests/community-pr-process.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.83%. Comparing base (b11884c) to head (a9227b4).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6905      +/-   ##
==========================================
- Coverage   86.14%   85.83%   -0.31%     
==========================================
  Files         894      981      +87     
  Lines       62486    63359     +873     
  Branches     8937     8960      +23     
==========================================
+ Hits        53830    54386     +556     
- Misses       5589     5891     +302     
- Partials     3067     3082      +15     

Flag	Coverage Δ
app-data	17.69% <ø> (+0.49%)	⬆️
app-ui-auth-tools	20.08% <ø> (+0.07%)	⬆️
app-ui-platform	16.17% <ø> (+0.13%)	⬆️
app-ui-vault	27.22% <ø> (-0.06%)	⬇️
authenticator	6.50% <ø> (+0.04%)	⬆️
lib-core-network-bridge	3.99% <ø> (-0.17%)	⬇️
lib-data-ui	1.11% <ø> (-0.05%)	⬇️

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