chore: KOF 1.5.0-rc1

[denis-ryzhkov]

• Part of Test KOF 1.5.0 RC #603
• Bumped versions.
• Applied bin/golangci-lint-v2.5.0 migrate
• Satisfied the linter.
• Set cache-dependency-path: kof-operator/go.sum in cached actions/setup-go
  and bumped CONTROLLER_TOOLS_VERSION from v0.16.1 to v0.19.0
  to fix CI-only error invalid array length -delta * delta (constant -256 of type int64)
• Switched .github/actions/setup-yq from wget to curl.
• Added cleanupOnDeletion: true to demo/clusters.

[Copilot]

Pull Request Overview

This is a release candidate (KOF 1.5.0-rc1) that updates dependencies and enforces stricter code quality standards through golangci-lint v2.5.0 migration and associated lint fixes.

• Upgraded golangci-lint from v1.64.7 to v2.5.0 and updated its configuration to use the new v2 syntax
• Updated Go toolchain and all major dependencies (Kubernetes, Prometheus, Grafana Operator, etc.)
• Applied automated lint fixes including replacing deprecated APIs and simplifying logic

Reviewed Changes

Copilot reviewed 18 out of 19 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
kof-operator/go.mod	Updated Go version to 1.25.1 and bumped all dependencies to latest versions
kof-operator/Makefile	Updated golangci-lint version and import path for v2
kof-operator/.golangci.yml	Migrated to golangci-lint v2 configuration syntax with new formatter/exclusion structure
kof-operator/test/utils/utils.go	Replaced deprecated nolint directive and used strings.ReplaceAll
kof-operator/internal/models/target/targets.go	Simplified method calls by removing redundant receiver references
kof-operator/internal/metrics/health.go	Improved error message clarity with "the" article
kof-operator/internal/controller/promxyservergroup_controller_test.go	Simplified ObjectMeta.Labels access
kof-operator/internal/controller/configmap_cluster_regional.go	Fixed Duration.Seconds() calls (removed redundant .Duration)
kof-operator/internal/controller/alerts_configmap_controller.go	Simplified boolean logic using De Morgan's law
demo/cluster/*.yaml	Updated template versions and added cleanupOnDeletion: true
.github/actions/setup-yq/action.yaml	Switched from wget to curl for consistency

[Copilot]

Pull Request Overview

Copilot reviewed 23 out of 24 changed files in this pull request and generated no new comments.