Disable k3d integration tests

[nkubala]

k3d integration tests have been failing with an error that seems to be unrelated to skaffold code, and it's causing CI to fail on many unrelated PRs. Let's disable the tests until we can diagnose and fix the issue.

[nkubala]

ref k3d-io/k3d#671

[codecov]

Codecov Report

Merging #6171 (1e59747) into master (c2b6deb) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6171      +/-   ##
==========================================
- Coverage   69.34%   69.29%   -0.06%     
==========================================
  Files         481      482       +1     
  Lines       18492    18523      +31     
==========================================
+ Hits        12824    12836      +12     
- Misses       4716     4733      +17     
- Partials      952      954       +2     

Impacted Files	Coverage Δ
pkg/skaffold/docker/image.go	78.13% <0.00%> (-1.40%)	⬇️
pkg/skaffold/event/v2/render.go	23.80% <0.00%> (ø)
pkg/skaffold/event/v2/metadata.go	89.33% <0.00%> (+0.14%)	⬆️
pkg/skaffold/event/v2/event.go	80.48% <0.00%> (+0.74%)	⬆️

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