Add a new config to speed up block sync

[yzang2019]

Describe your changes and provide context

This PR speed up block sync and fix a few issues:

1. The bpr pending request number is too high, leading to overuse of network and possible gaps
2. The peer pickup logic is not great, so that it would have a high chance to pick a slow peer or not responding peer, leading to constant timeout
3. We should never switch to consensus mode if we are behind, we should stick to the catch up mode

Testing performed to validate your change

[codecov]

Codecov Report

Attention: Patch coverage is 29.03226% with 22 lines in your changes missing coverage. Please review.

Project coverage is 58.08%. Comparing base (96d05f0) to head (d53293b).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/p2p/peermanager.go	33.33%	7 Missing and 3 partials ⚠️
node/setup.go	0.00%	5 Missing and 1 partial ⚠️
internal/blocksync/pool.go	33.33%	3 Missing and 1 partial ⚠️
internal/blocksync/reactor.go	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #244      +/-   ##
==========================================
- Coverage   58.21%   58.08%   -0.13%     
==========================================
  Files         249      249              
  Lines       34485    34510      +25     
==========================================
- Hits        20074    20046      -28     
- Misses      12825    12872      +47     
- Partials     1586     1592       +6     

Files with missing lines	Coverage Δ
config/config.go	63.11% <100.00%> (ø)
config/toml.go	51.35% <ø> (ø)
internal/blocksync/reactor.go	51.97% <33.33%> (ø)
internal/blocksync/pool.go	77.56% <33.33%> (-2.35%)	⬇️
node/setup.go	69.56% <0.00%> (-1.24%)	⬇️
internal/p2p/peermanager.go	79.31% <33.33%> (-0.83%)	⬇️

... and 12 files with indirect coverage changes