Change default Prometheus host to localhost

[utafrali]

Fixes #8297

Switched default Prometheus host from 0.0.0.0 to localhost for better security isolation. Updated the test assertion to check for localhost variants since the actual address can differ across environments.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.25%. Comparing base (ca41b47) to head (5479c22).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #8298   +/-   ##
=========================================
  Coverage     90.25%   90.25%           
- Complexity     7683     7684    +1     
=========================================
  Files           850      850           
  Lines         23190    23195    +5     
  Branches       2353     2354    +1     
=========================================
+ Hits          20930    20935    +5     
  Misses         1533     1533           
  Partials        727      727           

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[jack-berg]

Pushed 5479c22 to add a log to inform users not explicitly setting the host about the change in behavior. Logging at level info so its likely visible, but not needlessly alarming.

[utafrali]

Looks good, thanks for adding the log.

[otelbot]

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