Upgrade golangci-lint from v1 to v2

[sebrandon1]

Summary

• Update golangci-lint from v1.61.0 to v2.0.2
• Migrate .golangci.yml to v2 format

Changes Made

• Makefile: Updated version variable
• .golangci.yml: Converted to v2 format
  • Added version: "2" declaration
  • Moved gofmt to formatters.enable

Test plan

• CI linting passes with golangci-lint v2
• No new linting errors introduced

Tracking: redhat-best-practices-for-k8s/telco-bot#49

[openshift-ci]

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[openshift-ci]

@sebrandon1: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/verify-commits	ba1f1c0	link	false	/test verify-commits

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