fix(notifications_push_repository): Delete push subscription when account is deleted

[provokateurin]

Part of #2114

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.91%. Comparing base (586aef2) to head (20c0c0d).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2667      +/-   ##
==========================================
+ Coverage   28.90%   28.91%   +0.01%     
==========================================
  Files         372      372              
  Lines      136624   136644      +20     
==========================================
+ Hits        39492    39512      +20     
  Misses      97132    97132              

Flag	Coverage Δ		*Carryforward flag
account_repository	98.49% <100.00%> (+0.02%)	⬆️
cookie_store	99.48% <ø> (ø)		Carriedforward from 586aef2
dashboard_app	96.05% <ø> (ø)
dynamite	31.05% <ø> (ø)		Carriedforward from 586aef2
dynamite_end_to_end_test	61.69% <ø> (ø)		Carriedforward from 586aef2
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from 586aef2
interceptor_http_client	97.18% <ø> (ø)		Carriedforward from 586aef2
neon_dashboard	96.05% <ø> (ø)		Carriedforward from 586aef2
neon_framework	61.44% <ø> (ø)
neon_http_client	94.32% <ø> (ø)		Carriedforward from 586aef2
neon_notifications	100.00% <ø> (ø)		Carriedforward from 586aef2
neon_storage	94.66% <ø> (ø)		Carriedforward from 586aef2
neon_talk	99.45% <ø> (ø)		Carriedforward from 586aef2
nextcloud	24.33% <ø> (ø)		Carriedforward from 586aef2
notifications_app	97.43% <ø> (ø)
notifications_push_repository	98.19% <100.00%> (+0.07%)	⬆️
sort_box	90.90% <ø> (ø)		Carriedforward from 586aef2
talk_app	99.01% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.

Files with missing lines	Coverage Δ
...account_repository/lib/src/account_repository.dart	100.00% <100.00%> (ø)
...ository/lib/src/notifications_push_repository.dart	99.03% <100.00%> (+0.14%)	⬆️

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles

[Leptopoda]

I still don't like interlocking the repositories.
I think that the account_bloc should handle this. Once a LogoutEvent is emitted, the bloc should unregister the notifications and afterward remove the account from the repository.

[Leptopoda]

I think that running these callbacks in parallel should be ok.
The account_repo can't guarantee execution order anyway.

Please use a Future.wait