refactor(builder): Build IndexesManager on builders

[msbrogli]

Acceptance criteria

1. Build IndexesManager on builders.
2. Remove default value for Metrics.tx_storage.

[codecov]

Codecov Report

Merging #640 (91a476e) into master (0dcf3b5) will decrease coverage by 0.11%.
The diff coverage is 96.72%.

❗ Current head 91a476e differs from pull request most recent head 512ac62. Consider uploading reports for the commit 512ac62 to get more accurate results

@@            Coverage Diff             @@
##           master     #640      +/-   ##
==========================================
- Coverage   84.07%   83.96%   -0.11%     
==========================================
  Files         245      245              
  Lines       20282    20295      +13     
  Branches     2759     2762       +3     
==========================================
- Hits        17052    17041      -11     
- Misses       2635     2657      +22     
- Partials      595      597       +2     

Impacted Files	Coverage Δ
hathor/builder/builder.py	91.86% <94.59%> (+0.95%)	⬆️
hathor/builder/cli_builder.py	72.53% <100.00%> (-0.14%)	⬇️
hathor/indexes/manager.py	91.30% <100.00%> (-0.87%)	⬇️
hathor/metrics.py	86.30% <100.00%> (-0.09%)	⬇️
hathor/transaction/storage/cache_storage.py	94.07% <100.00%> (-0.09%)	⬇️
hathor/transaction/storage/memory_storage.py	91.17% <100.00%> (+0.13%)	⬆️
hathor/transaction/storage/rocksdb_storage.py	94.57% <100.00%> (-0.21%)	⬇️
hathor/transaction/storage/transaction_storage.py	90.85% <100.00%> (-0.33%)	⬇️

... and 15 files with indirect coverage changes