tests: flaky tests fixes

[algorandskiy]

Summary

1. TestP2PMakeHostAddressFilter listening on "0.0.0.0:0" was not ready for a builder having only a single interface with a public IPv4 so its actual listen address became this interface address. Fixed by ensuring if Addrs() return non-empty, all elements are public (failure).
2. Rewrote TestVotersReloadFromDiskAfterOneStateProofCommitted to use synchronous commits. Handled extra element in deferred commits queue by draining it before reloadLedger - a very first commit gets scheduled there because AddBlock -> AddValidatedBlock -> notifyCommit -> scheduleCommit is still being called, and reloadLedger does not reset the accountWriting wait group (failure).
3. goal-partkey-commands.sh fails for no good reason - output has all required strings but if echo "$OUTPIT" | grep -q "$STRING" fails to handle it as expected. I fixed possible whitespaces and fixed shellcheck. Not sure what else.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.26%. Comparing base (c6a433b) to head (5297b06).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6098      +/-   ##
==========================================
+ Coverage   55.80%   56.26%   +0.46%     
==========================================
  Files         489      489              
  Lines       69691    69691              
==========================================
+ Hits        38888    39214     +326     
+ Misses      28108    27816     -292     
+ Partials     2695     2661      -34     

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