Update the Helm chart to include WireMock 3.0.0 and use the official image

[oleg-nenashev]

Addresses #22 and #25

Submitter checklist

• [ ] Recommended: Join WireMock Slack to get any help in #help-contributing or a project-specific channel like #wiremock-java
• [ ] The PR request is well described and justified, including the body and the references
• [ ] The PR title represents the desired changelog entry
• [ ] The repository's code style is followed (see the contributing guide)
• [ ] Test coverage that demonstrates that the change works as expected
• [ ] For new features, there's necessary documentation in this pull request or in a subsequent PR to wiremock.org

[oleg-nenashev]

 Warning  Unhealthy  4m30s (x3 over 4m50s)  kubelet            Liveness probe failed: Get "http://10.244.0.2:9021/__admin/webapp": dial tcp 10.244.0.2:9021: connect: connection refused