🌱 Makefile: migrate lint-markdownlint to upstream provided image and markdownlint-cli2

[chrischdi]

What this PR does / why we need it:

• Replaces markdownlint-cli by markdownlint-cli2
• Makes use of the upstream provided image (but synced to CAPV's image repo) instead of self-building and pushing the image
• Allows to run lint-markdown on arm64
• Adds ./hack/markdownlint-sync-image.sh for syncing the image
  • Note: I think we cannot depend on the original image, e.g. due to image pull limits from dockerhub in CI.

For testing, use:

MARKDOWNLINT_CLI2_IMAGE_NAME=davidanson/markdownlint-cli2 make lint-markdown

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Part of #2126

[k8s-ci-robot]

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[k8s-ci-robot]

@chrischdi: 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-cluster-api-provider-vsphere-verify-main	628789b	link	true	/test pull-cluster-api-provider-vsphere-verify-main

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[chrischdi]

@chrischdi: 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-cluster-api-provider-vsphere-verify-main 628789b link true /test pull-cluster-api-provider-vsphere-verify-main
Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Expected to fail due to not yet synced image.

[chrischdi]

/close

[k8s-ci-robot]

@chrischdi: Closed this PR.

In response to this:

/close

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