fix: use testify instead of t.Fatal or t.Error in pkg package (part 1)

[mmorel-35]

Description

This uses testify instead of testing for t.Fatal or t.Error calls in pkg package

Related to #18972

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: mmorel-35
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[k8s-ci-robot]

Hi @mmorel-35. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.80%. Comparing base (3d46df1) to head (d623139).

Additional details and impacted files

see 25 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #18970      +/-   ##
==========================================
+ Coverage   68.77%   68.80%   +0.03%     
==========================================
  Files         420      420              
  Lines       35598    35598              
==========================================
+ Hits        24483    24494      +11     
+ Misses       9685     9681       -4     
+ Partials     1430     1423       -7     

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