Backport of add HOST_IP to mesh-gateway into release/1.0.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #1808 to be assessed for backporting due to the inclusion of the label backport/1.0.x.

🚨

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The person who merged in the original PR is:
@DanStough
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: POST https://api.github.com/repos/hashicorp/consul-k8s/merges: 409 Merge conflict []

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

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Changes proposed in this PR:

• Add HOST_IP environment variable back to mesh-gateway deployment
  Expansion of this var is supported according to the docs, but requires the var to actually be set: https://developer.hashicorp.com/consul/docs/connect/proxies/envoy#envoy_statsd_url

How I've tested this PR:

• Applied the change locally and verified that the pod manifest reflect the updated environment configuration

How I expect reviewers to test this PR:

• Apply the changes are verify that the pod manifests reflect the updated environment configuration

Note too sure the best way to add a test for this. Suggestions would be greatly appreciated.

Checklist:

• Tests added
• CHANGELOG entry added

  HashiCorp engineers only, community PRs should not add a changelog entry.
  Entries should use present tense (e.g. Add support for...)

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Overview of commits

• 1535190 - 7f54c36 - 64f9edc - 2d660e8 - 4a7d203 - a248c47 - d13e2f5 - 7e5f1a0 - 1248165