Remove gh setup from global proxy test

pr-checks/checks/global-proxy.yml

@@ -3,19 +3,6 @@ description: "Tests using a proxy specified by the https_proxy environment varia
 versions: ["linked", "nightly-latest"]
 container:
   image: ubuntu:22.04
-container-init-steps:
-  # These steps are required to initialise the `gh` cli in a container that doesn't
-  # come pre-installed with it. The reason for that is that this is later
-  # needed by the `prepare-test` workflow to find the latest release of CodeQL. 
-  name: Set up GitHub CLI
-  run: |
-    apt update
-    apt install -y curl libreadline8 gnupg2 software-properties-common zstd
-    curl -fsSL https://cli.github.com/packages/githubcli-archive-keyring.gpg | dd of=/usr/share/keyrings/githubcli-archive-keyring.gpg
-    apt-key add /usr/share/keyrings/githubcli-archive-keyring.gpg
-    apt-add-repository https://cli.github.com/packages
-    apt install -y gh
-  env: {}
 services:
   squid-proxy:
     image: ubuntu/squid:latest