fix(ci): fix lts image build

[MarlonGamez]

This PR removes the release-lts make target's dependency on the cross target. The `cross target is being removed as a dependency from targets as it's functionality is being moved to kokoro.

[aaron-prindle]

LGTM

[codecov]

Codecov Report

Merging #7000 (4c86d1c) into main (290280e) will decrease coverage by 1.71%.
The diff coverage is 56.96%.

@@            Coverage Diff             @@
##             main    #7000      +/-   ##
==========================================
- Coverage   70.48%   68.76%   -1.72%     
==========================================
  Files         515      554      +39     
  Lines       23150    25683    +2533     
==========================================
+ Hits        16317    17661    +1344     
- Misses       5776     6821    +1045     
- Partials     1057     1201     +144     

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 181 more

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