refactor: update default pruning strategy

[alexanderbez]

The default pruning strategy, specifically the total number of recent blocks to keep (currently 100), was decided on completely arbitrary.

I propose we change it to be enough blocks given that the typical block time is 5s and typical unbonding period is 21 days:
(3600*(24/5)) * 21 = 362880.

I propose this because anyone wishing to run an IBC relayer, which will be most chains, will have to be required to use custom to set it to this value anyway. So why not just make it the default and make it easier for operators.

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[amaury1093]

lgtm

[codecov]

Codecov Report

Merging #9859 (e3b1104) into master (afde096) will increase coverage by 0.01%.
The diff coverage is n/a.

❗ Current head e3b1104 differs from pull request most recent head ca6a8cd. Consider uploading reports for the commit ca6a8cd to get more accurate results

@@            Coverage Diff             @@
##           master    #9859      +/-   ##
==========================================
+ Coverage   63.46%   63.47%   +0.01%     
==========================================
  Files         568      568              
  Lines       53256    53271      +15     
==========================================
+ Hits        33800    33815      +15     
  Misses      17532    17532              
  Partials     1924     1924              

Impacted Files	Coverage Δ
store/types/pruning.go	51.85% <ø> (ø)
x/bank/types/balance.go	89.83% <0.00%> (+3.46%)	⬆️

[likhita-809]

lgtm