Backport of added make target for checking for hashicorppreview into release/1.2.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #2603 to be assessed for backporting due to the inclusion of the label backport/1.2.x.

The below text is copied from the body of the original PR.

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Changes proposed in this PR:

• Adds a make target to check for hashicorppreview images in the charts. This will help verify release steps.

How I've tested this PR:

Example output where hashicorppreview is found

$ make check-preview-containers
./charts/consul/Chart.yaml:19:      image: docker.mirror.hashicorp.services/hashicorppreview/consul-enterprise:1.17-dev
./charts/consul/Chart.yaml:21:      image: docker.mirror.hashicorp.services/hashicorppreview/consul-k8s-control-plane:1.3.0-dev
./charts/consul/Chart.yaml:23:      image: docker.mirror.hashicorp.services/hashicorppreview/consul-dataplane:1.3-dev
./charts/consul/values.yaml:69:  image: docker.mirror.hashicorp.services/hashicorppreview/consul:1.17-dev
./charts/consul/values.yaml:89:  imageK8S: docker.mirror.hashicorp.services/hashicorppreview/consul-k8s-control-plane:1.3.0-dev
./charts/consul/values.yaml:611:  imageConsulDataplane: docker.mirror.hashicorp.services/hashicorppreview/consul-dataplane:1.3-dev
charts contain hashicorppreview images

Example output where hashicorppreview is not found

$ make check-preview-containers
charts do not contain hashicorpreview images

How I expect reviewers to test this PR:

Checklist:

• Tests added
• CHANGELOG entry added

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Overview of commits

• 853a9d1 - 128d8a7