Stop using go-ipfs-blocksutil

[gammazero]

• Replace use of go-ipfs-blocksutil with go-test/random
• Remove remaining references to go-blockservice

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.97%. Comparing base (635e175) to head (0447fc3).

@@            Coverage Diff             @@
##             main     #656      +/-   ##
==========================================
+ Coverage   59.91%   59.97%   +0.06%     
==========================================
  Files         237      237              
  Lines       29955    29955              
==========================================
+ Hits        17947    17966      +19     
+ Misses      10395    10376      -19     
  Partials     1613     1613              

Files	Coverage Δ
bitswap/client/client.go	90.42% <ø> (+2.29%)	⬆️
blockservice/internal/tracing.go	100.00% <100.00%> (ø)

... and 13 files with indirect coverage changes