[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-python.sh

@@ -0,0 +1,34 @@
+#!/bin/bash -e
+################################################################################
+##  File:  install-python.sh
+##  Desc:  Install Python 3
+################################################################################
+
+set -e
+# Source the helpers for use with the script
+source $HELPER_SCRIPTS/etc-environment.sh
+source $HELPER_SCRIPTS/os.sh
+
+# Install Python, Python 3, pip, pip3
+apt-get install -y --no-install-recommends python3 python3-dev python3-pip python3-venv
+
+# Install pipx
+# Set pipx custom directory
+export PIPX_BIN_DIR=/opt/pipx_bin
+export PIPX_HOME=/opt/pipx
+python3 -m pip install pipx
+python3 -m pipx ensurepath
+# Update /etc/environment
+setEtcEnvironmentVariable "PIPX_BIN_DIR" $PIPX_BIN_DIR
+setEtcEnvironmentVariable "PIPX_HOME" $PIPX_HOME
+prependEtcEnvironmentPath $PIPX_BIN_DIR
+# Test pipx
+if ! command -v pipx; then
+    echo "pipx was not installed or not found on PATH"
+    exit 1
+fi
+
+# Adding this dir to PATH will make installed pip commands are immediately available.
+prependEtcEnvironmentPath '$HOME/.local/bin'
+
+invoke_tests "Tools" "Python"