Rename internal gateway container

What does this MR do and why?

This MR renames internal gateway container to make it easier to filter logs. Context: gitlab-com/gl-infra/k8s-workloads/tanka-deployments!821 (comment 1647182160)

We've already renamed zoekt-gateway to zoekt-external-gateway in the deployment, but that wasn't enough.

$ touch gitlab-gitlab-zoekt-0_gitlab_zoekt-gateway-ea3e7a7b692a2124e9553eac6bd50e0ca6eed76107e71d882641219e5097edd3.log
$ touch gitlab-gitlab-zoekt-gateway-76867775d6-bdr29_gitlab_zoekt-external-gateway-1dfed9128d1545d917befb15cc27a582ced4c652675bef98be2676193eef9cea.log
$ ls gitlab-gitlab-zoekt-*-external-gateway-*
gitlab-gitlab-zoekt-gateway-76867775d6-bdr29_gitlab_zoekt-external-gateway-1dfed9128d1545d917befb15cc27a582ced4c652675bef98be2676193eef9cea.log
$ ls gitlab-gitlab-zoekt-*-gateway-*
gitlab-gitlab-zoekt-0_gitlab_zoekt-gateway-ea3e7a7b692a2124e9553eac6bd50e0ca6eed76107e71d882641219e5097edd3.log
gitlab-gitlab-zoekt-gateway-76867775d6-bdr29_gitlab_zoekt-external-gateway-1dfed9128d1545d917befb15cc27a582ced4c652675bef98be2676193eef9cea.log

We still can't get the glob to match only internal gateway. I believe that after we rename the container in the stateful set to zoekt-internal-gateway we should be able to distinguish those.

How to set up and validate locally

1. Checkout the main branch

   git checkout main

2. Install the chart

   helm install gitlab-zoekt .

3. Check out the names of the containers in the stateful set

   kubectl get po gitlab-zoekt-0 -o yaml | yq -P '.spec.containers[].name'

4. Check out the branch of this MR

   git checkout rename-internal-gateway-container

5. Upgrade the chart

   helm upgrade gitlab-zoekt .

6. Check out the names of the containers in the stateful set. This time the gateway container should become zoekt-internal-gateway

   kubectl get po gitlab-zoekt-0 -o yaml | yq -P '.spec.containers[].name'

asciinema