Downloader - Set gRPC max (incoming) message size to server default

[mriccobene]

This PR tries to solve issue #734

[codecov]

Codecov Report

Merging #742 (3b2d7b2) into master (4f2c788) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #742      +/-   ##
==========================================
- Coverage   76.25%   76.21%   -0.04%     
==========================================
  Files         190      190              
  Lines       13052    13052              
  Branches     2118     2118              
==========================================
- Hits         9953     9948       -5     
- Misses       2211     2213       +2     
- Partials      888      891       +3     

Impacted Files	Coverage Δ
node/silkworm/rpc/completion_end_point.cpp	90.69% <0.00%> (-4.66%)	⬇️
core/silkworm/state/in_memory_state.cpp	92.18% <0.00%> (-0.53%)	⬇️
core/silkworm/trie/hash_builder.cpp	98.13% <0.00%> (-0.47%)	⬇️
core/silkworm/types/transaction.cpp	81.78% <0.00%> (-0.32%)	⬇️
core/silkworm/execution/evm.cpp	93.61% <0.00%> (-0.24%)	⬇️
node/silkworm/rpc/server/call.hpp	70.57% <0.00%> (+0.28%)	⬆️

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