Don't gather kerberos creds in pypykatz

[shreyamalviya]

What does this PR do?

Fixes #1771

PR Checklist

• Have you added an explanation of what your changes do and why you'd like to include them?
• Is the TravisCI build passing?
• Was the CHANGELOG.md updated to reflect the changes?
• Was the documentation framework updated to reflect the changes?
• Have you checked that you haven't introduced any duplicate code?

Testing Checklist

• Added relevant unit tests?
• Have you successfully tested your changes locally? Elaborate:

  Tested by exploiting Zerologon and checking the Island

• If applicable, add screenshots or log transcripts of the feature working
  

[codecov]

Codecov Report

Merging #1897 (d50b3f0) into develop (825fe33) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #1897   +/-   ##
========================================
  Coverage    54.90%   54.90%           
========================================
  Files          446      446           
  Lines        12637    12637           
========================================
  Hits          6938     6938           
  Misses        5699     5699           

Impacted Files	Coverage Δ
..._collectors/mimikatz_collector/pypykatz_handler.py	70.00% <ø> (ø)

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