chore: install gke-gcloud-auth-plugin in skaffold images

[briandealwis]

Fixes: #7059

Install gke-gcloud-auth-plugin into gcr.io/k8s-skaffold/skaffold images.

cc: @ekupershlak

[codecov]

Codecov Report

Merging #7060 (bc7d8a9) into main (290280e) will decrease coverage by 1.70%.
The diff coverage is 56.96%.

@@            Coverage Diff             @@
##             main    #7060      +/-   ##
==========================================
- Coverage   70.48%   68.77%   -1.71%     
==========================================
  Files         515      554      +39     
  Lines       23150    25876    +2726     
==========================================
+ Hits        16317    17796    +1479     
- Misses       5776     6872    +1096     
- Partials     1057     1208     +151     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/deploy.go	52.00% <ø> (-1.85%)	⬇️
cmd/skaffold/app/cmd/dev.go	84.61% <0.00%> (ø)
cmd/skaffold/app/cmd/render.go	36.66% <0.00%> (-4.72%)	⬇️
cmd/skaffold/skaffold.go	0.00% <0.00%> (ø)
cmd/skaffold/app/cmd/inspect_tests.go	62.50% <14.28%> (-1.14%)	⬇️
cmd/skaffold/app/cmd/lsp.go	28.12% <28.12%> (ø)
cmd/skaffold/app/cmd/fix.go	68.85% <40.00%> (-7.62%)	⬇️
cmd/skaffold/app/cmd/lint.go	42.85% <42.85%> (ø)
cmd/skaffold/app/cmd/find_configs.go	48.88% <50.00%> (+0.24%)	⬆️
cmd/skaffold/app/skaffold.go	76.19% <70.00%> (-8.43%)	⬇️
... and 186 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1ac7448...bc7d8a9. Read the comment docs.