Missing final slog.Error for KEV validations

[cleong14]

KEV validations are missing final slog.Error.

• Grype KEV:

  gatecheck/pkg/gatecheck/validate.go

  Lines 228 to 230 in 4bdc53d

  	if foundKevMatch {
  	return false
  	}

• CycloneDX KEV:

  gatecheck/pkg/gatecheck/validate.go

  Lines 258 to 260 in 4bdc53d

  	if foundKevMatch {
  	return false
  	}

KEV validations should more closely match EPSS validations.

• Example EPSS validation final slog.Error:

  gatecheck/pkg/gatecheck/validate.go

  Lines 371 to 377 in 4bdc53d

  	if len(badCVEs) > 0 {
  	slog.Error("cve(s) with epss scores over limit",
  	"over_limit_cves", len(badCVEs),
  	"epss_limit_score", config.Grype.EPSSLimit.Score,
  	)
  	return false
  	}