Removing mac setup guide

Putting it in runner repo instead

doc/ci/runners/build_cloud/macos/setup.md

----
-stage: Verify
-group: Runner
-info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
----
-
-# Set up macOS runners
-
-To run a CI/CD job on a macOS runner, complete the following steps in order.
-
-When you're done, GitLab Runner will be running on your macOS machine
-and an individual runner will be ready to process jobs.
-
-- Change the system shell to Bash.
-- Install Homebrew, rbenv, and GitLab Runner.
-- Configure rbenv and install Ruby.
-- Install Xcode.
-- Register a runner.
-- Configure CI/CD.
-
-## Prerequisites
-
-Before you begin:
-
-- Install a recent version of macOS. This guide was developed on 11.4.
-- Ensure you have terminal or SSH access to the machine.
-
-## Change the system shell to Bash
-
-Newer versions of macOS ship with Zsh as the default shell.
-You must change it to Bash.
-
-1. Connect to your machine and determine the default shell:
-
-   ```shell
-   echo $shell
-   ```
-
-1. If the result is not `/bin/bash`, change the shell by running:
-  
-   ```shell
-   chsh -s /bin/bash
-   ```
-
-1. Enter your password.
-1. Restart your terminal or reconnect by using SSH.
-1. Run `echo $SHELL` again. The result should be `/bin/bash`.
-
-## Install Homebrew, rbenv, and GitLab Runner
-
-The runner needs certain environment options to connect to the machine and run a job.
-
-1. Install the [Homebrew package manager](https://brew.sh/):
-
-   ```shell
-   /bin/bash -c "$(curl "https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh")"
-   ```
-
-1. Set up [`rbenv`](https://github.com/rbenv/rbenv), which is a Ruby version manager, and GitLab Runner:
-  
-   ```shell
-   brew install rbenv gitlab-runner
-   brew services start gitlab-runner
-   ```
-
-## Configure rbenv and install Ruby
-
-Now configure rbenv and install Ruby.
-
-1. Add rbenv to the Bash environment:
-
-   ```shell
-   echo 'if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi' >> ~/.bash_profile
-   source ~/.bash_profile
-   ```
-
-1. Install Ruby 2.74 and set it as the machine's global default:
-
-   ```shell
-   rbenv install 2.7.4
-   rbenv global 2.7.4
-   ```
-
-## Install Xcode
-
-Now install and configure Xcode.
-
-1. Go to one of these locations and install Xcode:
-
-   - The Apple App Store.
-   - The [Apple Developer Portal](https://developer.apple.com/download/all/?q=xcode).
-   - [`xcode-install`](https://github.com/xcpretty/xcode-install). This project aims to make it easier to download various
-     Apple dependencies from the command line.
-
-1. Agree to the license and install the recommended additional components.
-   You can do this by opening Xcode and following the prompts, or by running the following command in the terminal:
-
-   ```shell
-   sudo xcodebuild -runFirstLaunch
-   ```
-
-1. Update the active developer directory so that Xcode loads the proper command line tools during your build:
-
-   ```shell
-   sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
-   ```
-
-### Register a runner
-
-Now register a runner to start picking up your CI/CD jobs.
-
-1. In GitLab, on the top bar, select **Menu > Projects** or **Menu > Group** to find your project or group.
-1. On the left sidebar, select **Settings > CI/CD**.
-1. Expand **Runners**.
-1. Note the URL and registration token.
-1. In a terminal, start the interactive setup:
-
-   ```shell
-   gitlab-runner register
-   ```
-
-1. Enter the GitLab URL.
-1. Enter the registration token.
-1. Enter a description for the runner.
-   You will use the description to identify the runner in GitLab, and the name is associated with jobs executed on this instance.
-
-1. Enter tags, which direct specific jobs to specific instances. You will use these tags later to ensure macOS jobs
-   run on this macOS machine. In this example, enter:
-
-   ```shell
-   macos
-   ```
-
-1. Type `shell` to select the shell [executor](https://docs.gitlab.com/runner/executors/).
-
-A success message is displayed:
-
-```shell
-> Runner registered successfully. Feel free to start it, but if it's running already the config should be automatically reloaded!
-```
-
-To view the runner, go to **Settings > CI/CD** and expand **Runners**.
-
-### Configure CI/CD
-
-In your GitLab project, configure CI/CD and start a build. You can use this sample `.gitlab-ci.yml` file.
-Notice the tags match the tags you used to register the runner.
-
-```yaml
-stages:
-  - build
-  - test
-
-variables:
-  LANG: "en_US.UTF-8"
-
-before_script:
-  - gem install bundler
-  - bundle install
-  - gem install cocoapods
-  - pod install
-
-build:
-  stage: build
-  script:
-    - bundle exec fastlane build
-  tags:
-    - macos
-
-test:
-  stage: test
-  script:
-    - bundle exec fastlane test
-  tags:
-    - macos
-```
-
-The macOS runner should now build your project.