[ubuntu] Rename build scripts (#8866)

* [ubuntu] Rename build scripts

* [ubuntu] Change reboot to inline shell

* [ubuntu] Move disk space validation to pester tests

* [ubuntu] Rename helper and tests files

* [ubuntu] Changes to cleanup, post-deployment and r scripts

images/ubuntu/scripts/build/install-github-cli.sh

@@ -0,0 +1,22 @@
+#!/bin/bash -e
+################################################################################
+##  File:  install-github-cli.sh
+##  Desc:  Install GitHub CLI
+##         Must be run as non-root user after homebrew
+##  Supply chain security: GitHub CLI - checksum validation
+################################################################################
+
+# Source the helpers for use with the script
+source $HELPER_SCRIPTS/install.sh
+
+# Download GitHub CLI
+URL=$(get_github_package_download_url "cli/cli" "contains(\"linux\") and contains(\"amd64\") and contains(\".deb\")")
+download_with_retries "${URL}" "/tmp" "gh_cli_linux_amd64.deb"
+# Supply chain security - GitHub CLI
+hash_url=$(get_github_package_download_url "cli/cli" "contains(\"checksums.txt\")")
+external_hash=$(get_hash_from_remote_file "${hash_url}" "linux_amd64.deb")
+use_checksum_comparison "/tmp/gh_cli_linux_amd64.deb" "${external_hash}"
+# Install GitHub CLI
+apt install /tmp/gh_cli_linux_amd64.deb
+
+invoke_tests "CLI.Tools" "GitHub CLI"