remove image utils pkg from ut

[ColdsteelRail]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

6. Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.98%. Comparing base (148e0af) to head (8805ba7).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #288   +/-   ##
=======================================
  Coverage   65.98%   65.98%           
=======================================
  Files          78       78           
  Lines        5647     5647           
=======================================
  Hits         3726     3726           
- Misses       1560     1561    +1     
+ Partials      361      360    -1     

Flag	Coverage Δ
unittests	65.98% <ø> (ø)

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