fix: prune stale x/foundation proposals at voting period end

[0Tech]

Description

The specification #721 says aborted and withdrawn proposals must be pruned at their voting period end. This patch addresses the difference in logic from the documentation's.

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov]

Codecov Report

Merging #730 (abd7e43) into main (5ed82db) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #730      +/-   ##
==========================================
- Coverage   61.96%   61.95%   -0.02%     
==========================================
  Files         877      877              
  Lines       98764    98819      +55     
==========================================
+ Hits        61200    61219      +19     
- Misses      33955    33997      +42     
+ Partials     3609     3603       -6     

Impacted Files	Coverage Δ
x/foundation/client/testutil/query.go	100.00% <100.00%> (ø)
x/foundation/keeper/proposal.go	83.70% <100.00%> (+0.76%)	⬆️
x/token/validation.go	70.90% <0.00%> (-20.00%)	⬇️
x/token/msgs.go	28.42% <0.00%> (-4.07%)	⬇️
x/collection/msgs.go	39.62% <0.00%> (-3.34%)	⬇️
crypto/keys/internal/ecdsa/privkey.go	84.21% <0.00%> (+1.75%)	⬆️