Migrate to golangci-lint/v2

[renormalize]

How to categorize this PR?

/area dev-productivity
/kind task

What this PR does / why we need it:

• Upgrade the golangci-lint tool to v2 in hack/tools.mk
• Converts the .golangci.yaml file to v2
• Fixes linting errors

Special notes for your reviewer:

cc @Shreyas-s14

Release note:

NONE

[gardener-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign shreyas-s-rao for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[gardener-prow]

@renormalize: 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
pull-etcd-druid-api-unit	ef45951	link	false	/test pull-etcd-druid-api-unit

Full PR test history. Your PR dashboard. Command help for this repository.
Please help us cut down on flakes by linking this test failure to an open flake report or filing a new flake report if you can't find an existing one. Also see our testing guideline for how to avoid and hunt flakes.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[renormalize]

Unit tests are failing, will update golangci-lint version in GitHub Actions as well.

[gardener-robot]

@Shreyas-s14 You have pull request review open invite, please check