refactor(core-state): log milestone change

[rainydio]

Summary

Simply log milestone change.

Checklist

• Ready to be merged

[codecov]

Codecov Report

Merging #3797 into develop will decrease coverage by 5.76%.
The diff coverage is 50.00%.

@@             Coverage Diff             @@
##           develop    #3797      +/-   ##
===========================================
- Coverage    96.86%   91.10%   -5.77%     
===========================================
  Files          616      616              
  Lines        13861    13863       +2     
  Branches      1672     1672              
===========================================
- Hits         13427    12630     -797     
- Misses         145      947     +802     
+ Partials       289      286       -3     

Flag	Coverage Δ
#functional	6.21% <0.00%> (-0.02%)	⬇️
#integration	10.02% <0.00%> (-0.01%)	⬇️
#unit	89.41% <50.00%> (-5.77%)	⬇️

Impacted Files	Coverage Δ
packages/core-state/src/stores/state.ts	22.34% <50.00%> (-77.66%)	⬇️
packages/core-state/src/dpos/dpos.ts	0.00% <0.00%> (-100.00%)	⬇️
packages/core-state/src/block-state.ts	0.00% <0.00%> (-100.00%)	⬇️
packages/core-state/src/state-builder.ts	0.00% <0.00%> (-100.00%)	⬇️
packages/core-state/src/stores/blocks.ts	0.00% <0.00%> (-100.00%)	⬇️
packages/core-state/src/service-provider.ts	0.00% <0.00%> (-100.00%)	⬇️
packages/core-state/src/stores/transactions.ts	0.00% <0.00%> (-100.00%)	⬇️
packages/core-state/src/transaction-validator.ts	0.00% <0.00%> (-100.00%)	⬇️
...ackages/core-state/src/dpos/dpos-previous-round.ts	0.00% <0.00%> (-100.00%)	⬇️
...s/core-state/src/actions/build-delegate-ranking.ts	0.00% <0.00%> (-100.00%)	⬇️
... and 14 more

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