fix: resolve issue where verify incorrectly failed when run with multiple modules where any module didn't have verify test cases

[aaron-prindle]

fixes #8368

Repro method:
root skaffold.yaml

apiVersion: skaffold/v4beta1
kind: Config
requires:
  - path: ./verify-none/skaffold.yaml
verify:
  - name: alpine
    container: 
      name: alpine
      image: alpine
      command: ["/bin/sh"]
      args: ["-c", "echo hello"]

/verify-none/skaffold.yaml file

apiVersion: skaffold/v4beta1
kind: Config
deploy:
  kubectl: {}

before fix PR
aprindle@aprindle-ssd ~/8368-issue $ skaffold verify
invalid skaffold config: verify command expects non-zero number of test cases

after fix PR
aprindle@aprindle-ssd ~/8368-issue $ skaffold verify
Tags used in verification:
latest: Pulling from library/alpine
Digest: sha256:f271e74b17ced29b915d351685fd4644785c6d1559dd1f2d4189a5e851ef753a
Status: Image is up to date for alpine:latest
[alpine] hello

[codecov]

Codecov Report

Merging #8369 (a2c0bcf) into main (290280e) will decrease coverage by 4.60%.
The diff coverage is 54.85%.

@@            Coverage Diff             @@
##             main    #8369      +/-   ##
==========================================
- Coverage   70.48%   65.89%   -4.60%     
==========================================
  Files         515      605      +90     
  Lines       23150    29819    +6669     
==========================================
+ Hits        16317    19648    +3331     
- Misses       5776     8699    +2923     
- Partials     1057     1472     +415     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/completion.go	13.04% <0.00%> (-1.25%)	⬇️
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/credits/export.go	0.00% <0.00%> (ø)
cmd/skaffold/app/cmd/deploy.go	40.90% <0.00%> (-12.94%)	⬇️
cmd/skaffold/app/cmd/generate_pipeline.go	60.00% <ø> (ø)
cmd/skaffold/app/cmd/inspect_modules.go	65.00% <ø> (ø)
cmd/skaffold/app/cmd/inspect_profiles.go	66.66% <ø> (ø)
... and 416 more

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[gsquared94]

lgtm.