chore: bump schema version to v4beta8

[renzodavid9]

Related: #9139

Description
Upgrade schema to v4beta8 needed for #9139.

All the files in this PR were auto generated from running hack/new-version.sh (following the schema change guide except for the change in the pinned version for builder images in examples/dev-journey-buildpacks/skaffold.yaml and integration/examples/dev-journey-buildpacks/skaffold.yaml; there was a test reporting a problem running the example.

[codecov]

Codecov Report

Merging #9140 (f491ba8) into main (290280e) will decrease coverage by 7.15%.
Report is 1043 commits behind head on main.
The diff coverage is 48.33%.

@@            Coverage Diff             @@
##             main    #9140      +/-   ##
==========================================
- Coverage   70.48%   63.33%   -7.15%     
==========================================
  Files         515      630     +115     
  Lines       23150    32413    +9263     
==========================================
+ Hits        16317    20530    +4213     
- Misses       5776    10316    +4540     
- Partials     1057     1567     +510     

Files	Coverage Δ
cmd/skaffold/app/cmd/commands.go	97.61% <100.00%> (+0.35%)	⬆️
cmd/skaffold/app/cmd/config.go	100.00% <100.00%> (ø)
cmd/skaffold/app/cmd/config/list.go	65.21% <ø> (ø)
cmd/skaffold/app/cmd/config/set.go	88.72% <ø> (ø)
cmd/skaffold/app/cmd/config/util.go	54.28% <ø> (ø)
cmd/skaffold/app/cmd/credits.go	100.00% <ø> (ø)
cmd/skaffold/app/cmd/debug.go	100.00% <100.00%> (ø)
cmd/skaffold/app/cmd/flags.go	93.00% <100.00%> (+2.18%)	⬆️
cmd/skaffold/app/cmd/generate_pipeline.go	60.00% <ø> (ø)
cmd/skaffold/app/cmd/init.go	100.00% <100.00%> (ø)
... and 41 more

... and 434 files with indirect coverage changes

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