Start test validator bound to localhost by default (rather than all interfaces)

[alexpyattaev]

Problem

Test-validator would bind to all interfaces by default which is insecure

Summary of Changes

• Change test-validator to bind to localhost by default

Context

#5802 tried to do the same but was poorly scoped and as a result had a problematic change which made it possible to get binding of ports on top of already bound ones.
This resulted in #5856 to revert, but RCA there was not correct (test-validator binding had nothing to do with the issues there).

The logic changes to cluster-info moved into separate PR #5832

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 82.9%. Comparing base (7f48e52) to head (a781797).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master    #5862     +/-   ##
=========================================
- Coverage    82.9%    82.9%   -0.1%     
=========================================
  Files         830      830             
  Lines      377199   377199             
=========================================
- Hits       312917   312895     -22     
- Misses      64282    64304     +22     

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[gregcusack]

looks mostly good. you may have to rebase this once #5855 is merged. also would delete the extra line added after parsing bind_address

[alexpyattaev]

Rebased, now its pretty trivial.

[joncinque]

Apologies for the fly-by review, but is this a breaking change? If so, can you add an entry to the changelog about this new behavior and how to restore the old behavior if needed?