Add tests for ListHosts() and DeleteHost()

[BruceAko]

Description

Replaces unit tests that were previously removed.

Related Issue

Motivation and Context

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 35.81%. Comparing base (eb4e101) to head (8b2abcf).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3604      +/-   ##
==========================================
+ Coverage   35.57%   35.81%   +0.23%     
==========================================
  Files         339      339              
  Lines       37190    37190              
==========================================
+ Hits        13231    13320      +89     
+ Misses      23120    23031      -89     
  Partials      839      839              

Flag	Coverage Δ
unittests	35.81% <ø> (+0.23%)	⬆️

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see 1 file with indirect coverage changes

[gaius-qi]

LGTM