Fix go:S1192: String literals should not be duplicated #416

Summary

Sonar rule go:S1192 flags string literals that appear 3+ times in a package, requiring them to be extracted as named constants to reduce duplication and simplify future refactoring.

Changes

• Extracted "(/|$)(.*)" → ingressPathSuffix constant in kaoto_controller_action_expose_ingress.go
• Extracted "NotRequires" → reasonNotRequires constant (same file)
• Extracted "Failure" → reasonFailure constant in a new shared constants.go (used across kaoto_controller.go, kaoto_controller_action_deploy.go, kaoto_controller_action_expose_ingress.go, kaoto_controller_action_expose_route.go, kaoto_controller_action_expose_service.go)
• Re-enabled the goconst linter in .golangci.yml (it was disabled since the initial setup commit with no documented reason; the ignore-tests: true setting was already pre-configured, indicating the intent to use it)

Prevention: go:S1192 — String literals should not be duplicated

• Go equivalent: goconst linter (autofixable: no)
• Previously enabled in repo: no (explicitly disabled in .golangci.yml)
• Status after this PR: enabled — goconst is now active and will catch future occurrences at lint time