Add HOST_IP environment variable to consul_dataplane_sidecar.go

[nathancoleman]

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