Backport of Add HOST_IP environment variable to consul_dataplane_sidecar.go into release/1.5.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #4277 to be assessed for backporting due to the inclusion of the label backport/1.5.x.

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

---

Note

This is sourced from #3916. I needed to open here so that CI requiring tokens that are unavailable in forks can run

Changes proposed in this PR

• Add HOST_IP environment variable to consul_dataplane_sidecar.go

This environment variable must be set in order to utilize HOST_IP as part of statsd or dogstatsd sinks. If this variable is unset and the sink is configured to use HOST_IP, the sidecar won't start and pods won't come up healthy.

How I've tested this PR

• Unit tests
• Deployed and tested a local build to our cluster and confirmed that injected pods now come up healthy and have the HOST_IP variable set as expected

How I expect reviewers to test this PR

• The unit tests should do it

  Reference to similar change for mesh-gateway deployments:

  • consul-k8s/CHANGELOG.md

    Line 763 in 8ac97bf

    * helm: add missing `$HOST_IP` environment variable to to mesh gateway deployments. [[GH-1808](https://github.com/hashicorp/consul-k8s/issues/1808)]

  • add HOST_IP to mesh-gateway #1808

Checklist

• Tests added
• CHANGELOG entry added

---

Overview of commits

• 6982b65 - 63df118 - fadb91e - 6e07105 - 7f7aa40 - 2bae8a5 - f20395b - cc1a640 - fbee95e - 9dc8708