Support proxy option for the Gitlab Agent
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This content sets the overall vision for the feature and serves as the release notes that will populate in various places, including the [release post blog](https://about.gitlab.com/releases/categories/releases/) and [Gitlab project releases](https://gitlab.com/gitlab-org/gitlab/-/releases). " --> Users' Kubernetes clusters can often access GitLab only through a proxy. Until now, the GitLab agent for Kubernetes did not support proxied connections. We added support for extra environment variables to the `agentk` Helm package to support proxied connections. ### Problem to solve Some of our K8S clusters have restricted internet access and must use a Squid proxy to reach the internet The Gitlab K8S agents require internet access and do not have a proxy option. ### Proposal ##### Update the Agent to support the ability to use a proxy for connecting to the internet - Add support for the industry-standard `HTTP_PROXY`, `HTTPS_PROXY`, and `NO_PROXY` environment variables? But this might be inconsistent with the fact that everything is configurable via the configuration file. Maybe support both (config in file overrides the env variables)? - Configuration should be applied to ALL outbound connections: kas, kubernetes API, Cilium, etc ##### Document how to use the new functionality ### Intended users <!-- Who will use this feature? If known, include any of the following: types of users (e.g. Developer), personas, or specific company roles (e.g. Release Manager). It's okay to write "Unknown" and fill this field in later. 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