test: un-shadow loadgen privateKeys var

[brianolson]

Summary

I am sad that go vet didn't have a warning about this shadowing of a variable name.

Test Plan

Manual test tool was tested manually.

[codecov]

Codecov Report

Merging #4380 (defbd4b) into master (60fb4f6) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4380   +/-   ##
=======================================
  Coverage   55.60%   55.60%           
=======================================
  Files         403      403           
  Lines       50801    50801           
=======================================
+ Hits        28248    28250    +2     
+ Misses      20159    20156    -3     
- Partials     2394     2395    +1     

Impacted Files	Coverage Δ
ledger/blockqueue.go	85.63% <0.00%> (-2.88%)	⬇️
agreement/cryptoVerifier.go	67.60% <0.00%> (-2.12%)	⬇️
agreement/proposalManager.go	96.07% <0.00%> (-1.97%)	⬇️
data/transactions/verify/txn.go	43.85% <0.00%> (-0.88%)	⬇️
ledger/acctonline.go	78.47% <0.00%> (-0.53%)	⬇️
catchup/service.go	68.88% <0.00%> (-0.50%)	⬇️
network/wsNetwork.go	64.70% <0.00%> (-0.20%)	⬇️
cmd/tealdbg/debugger.go	73.49% <0.00%> (+0.80%)	⬆️
data/abi/abi_type.go	88.62% <0.00%> (+0.94%)	⬆️
util/db/dbutil.go	50.30% <0.00%> (+1.21%)	⬆️
... and 3 more

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more