Add declarative_validation_test.go under autoscaling/scale/ and apps/scale/
that invoke ValidateScaleUpdate via VerifyUpdateValidationEquivalenceFunc.
The tests observe the rules declared by the generated fixtures, satisfying
AssertDeclarativeCoverage for autoscaling/v1.Scale, apps/v1beta1.Scale,
and apps/v1beta2.Scale.
Remove the autoscaling/v1.Scale, apps/v1beta1.Scale, and apps/v1beta2.Scale
entries from coverage-allowlist.yaml, then regenerate declarative-validation
test fixtures so the corresponding RegisterDeclaredRules calls and TestMain
files are emitted under autoscaling/scale/ and apps/scale/.