koord-descheduler: fix externally created MigrationJob not using default mode

[eahydra]

Ⅰ. Describe what this PR does

The migrationController in koord-descheduler does not support external created MigrationJob using default mod if the job does not set the spec.Mode. This PR fixes the issue.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how to verify it

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.02 🎉

Comparison is base (1eedb9b) 66.80% compared to head (d0b414d) 66.83%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1152      +/-   ##
==========================================
+ Coverage   66.80%   66.83%   +0.02%     
==========================================
  Files         271      271              
  Lines       29607    29608       +1     
==========================================
+ Hits        19779    19788       +9     
+ Misses       8419     8413       -6     
+ Partials     1409     1407       -2     

Flag	Coverage Δ
unittests	66.83% <100.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...kg/descheduler/controllers/migration/controller.go	65.62% <100.00%> (+0.73%)	⬆️
pkg/descheduler/evictions/evictions.go	90.81% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[ZiMengSheng]

/lgtm

[hormes]

/approve

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hormes

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• pkg/descheduler/OWNERS [hormes]

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