Fix to also remove VoterParams and LastProofHash in PruneStates

[Mdaiki0730]

Description

Function LoadVoters(), if valInfo is pruned at the input height, the function will return directly without querying voteParams and proofHash at the end of this function, which makes the permanent persistence of voteParams and proofHash useless.

I would prefer to prune the aforementioned VoterParams and LastProofHash in the function PruneStates()

PR Check List

• If you intend to keep these as history, we won't need this implementation.

[codecov]

Codecov Report

Merging #502 (46de8e5) into main (e6f57a1) will increase coverage by 0.08%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #502      +/-   ##
==========================================
+ Coverage   65.39%   65.48%   +0.08%     
==========================================
  Files         278      278              
  Lines       37995    38003       +8     
==========================================
+ Hits        24846    24885      +39     
+ Misses      11328    11309      -19     
+ Partials     1821     1809      -12     

Impacted Files	Coverage Δ
state/store.go	53.45% <100.00%> (+2.07%)	⬆️
crypto/sr25519/pubkey.go	35.89% <0.00%> (-7.70%)	⬇️
mempool/reactor.go	78.57% <0.00%> (-1.10%)	⬇️
p2p/switch.go	65.08% <0.00%> (-0.83%)	⬇️
p2p/conn/connection.go	79.80% <0.00%> (-0.20%)	⬇️
consensus/state.go	73.67% <0.00%> (+0.40%)	⬆️
consensus/reactor.go	75.37% <0.00%> (+1.14%)	⬆️
blockchain/v0/pool.go	79.58% <0.00%> (+1.55%)	⬆️
privval/signer_listener_endpoint.go	91.26% <0.00%> (+2.38%)	⬆️
... and 2 more