Fixes "file exists" error from CNI bins when upgrading k3s

[brandond]

Proposed Changes

Unlink existing CNI bin symlinks to avoid "file exists" error when upgrading K3s from an existing version with stable CNI bin support.

Also added support for enabling debug logging early in startup of the self-extracting wrapper; this was not being done early enough to capture debug level logs from the extract function.

Types of Changes

bugfix

Verification

• see linked issue comment

Testing

Linked Issues

• CNI bin dir changes with K3s version #10869 (comment)

User-Facing Change

Further Comments

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.15%. Comparing base (c0d661b) to head (b44751e).
Report is 2 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (c0d661b) and HEAD (b44751e). Click for more details.

HEAD has 2 uploads less than BASE

Flag	BASE (c0d661b)	HEAD (b44751e)
e2etests	8	6

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11123      +/-   ##
==========================================
- Coverage   48.72%   42.15%   -6.58%     
==========================================
  Files         178      178              
  Lines       14813    18498    +3685     
==========================================
+ Hits         7218     7797     +579     
- Misses       6288     9492    +3204     
+ Partials     1307     1209      -98     

Flag	Coverage Δ
e2etests	34.28% <ø> (-11.79%)	⬇️
inttests	34.61% <ø> (?)
unittests	13.11% <ø> (-0.44%)	⬇️

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