Backport of [NET-6466] Remove secrets from termgw role into release/1.3.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #3928 to be assessed for backporting due to the inclusion of the label backport/1.3.x.

🚨

Warning automatic cherry-pick of commits failed. If the first commit failed,
you will see a blank no-op commit below. If at least one commit succeeded, you
will see the cherry-picked commits up to, not including, the commit where
the merge conflict occurred.

The person who merged in the original PR is:
@jm96441n
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: unable to process merge commit: "d5c39d918b1f8e3caec230cd43779fd86bb8c061", automatic backport requires rebase workflow

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

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Changes proposed in this PR

• remove secrets access from terminating gateway as this is no longer needed

How I've tested this PR

1. build a local version of the control plane by running make dev-docker from the root of this repo
2. clone the following gist https://gist.github.com/jm96441n/8671cc5e73bf950955c96f7cd3281694
3. checkout this branch in consul-k8s repo on your machine
4. in start.sh replace the value for CONSUL_K8S_CHART_LOCATION with the path to the helm charts in consul-k8s on your system
5. run start.sh
6. once all the services are up exec into the bender service using:

kubectl exec -i -t $(kubectl get pods --selector=app=bender -o jsonpath='{.items[*].metadata.name}') -c bender -- /bin/sh

6. install curl onto the container using apk add curl
7. contact the zoidberg service fronted by the termgw using curl zoidberg.virtual.consul

How I expect reviewers to test this PR

Read the code, follow the above steps

Checklist

• Tests added
• CHANGELOG entry added

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Overview of commits

• 975434f - 4e61f68 - d5c39d9 - 5491ffd - 238e548 - 8308f27 - 5ef72f3