Improve ubuntu upgrade bash scripts

[jovial]

• Fix checking of undefined variables
• More quoting

Concrete issue was that it failed to correctly check KAYOBE_PATH was set.

[gemini-code-assist]

Code Review

This pull request improves the robustness of the Ubuntu upgrade scripts by fixing checks for undefined variables and adding quoting, which are great improvements. The changes correctly address the issues described.

I've added a couple of suggestions on tools/ubuntu-upgrade-infra-vm.sh to make the scripts even more concise and maintainable by using more idiomatic bash constructs. These suggestions also apply to the other scripts (ubuntu-upgrade-overcloud.sh, ubuntu-upgrade-seed-hypervisor.sh, ubuntu-upgrade-seed.sh) as they share similar code blocks. Applying these changes across all scripts would reduce code duplication and improve overall consistency.

[gemini-code-assist]

For checking required environment variables, you can use parameter expansion to make the code more concise and idiomatic. This will check if the variable is set and not empty, and if not, it will print the error message to stderr and exit the script due to set -e. This pattern can be applied to the other scripts as well.

Suggested change

	if [[ -z "$KAYOBE_PATH" ]]; then
	echo "Environment variable \$KAYOBE_PATH is not defined"
	exit 2
	fi
	if [[ ! $KAYOBE_CONFIG_PATH ]]; then
	if [[ -z "$KAYOBE_CONFIG_PATH" ]]; then
	echo "Environment variable \$KAYOBE_CONFIG_PATH is not defined"
	exit 2
	fi
	: "${KAYOBE_PATH:?Environment variable KAYOBE_PATH is not defined}"
	: "${KAYOBE_CONFIG_PATH:?Environment variable KAYOBE_CONFIG_PATH is not defined}"

[gemini-code-assist]

This logic for setting ANSIBLE_ROLES_PATH can be simplified to be less repetitive. By preparing the new value in a temporary variable, you can avoid duplicating the set -x/export/set +x block. This refactoring improves readability and maintainability, and can be applied to the other scripts as well.

Suggested change

	if [[ -z "$ANSIBLE_ROLES_PATH" ]]; then
	set -x
	export ANSIBLE_ROLES_PATH=$KAYOBE_PATH/ansible/roles
	export ANSIBLE_ROLES_PATH="$KAYOBE_PATH/ansible/roles"
	set +x
	else
	set -x
	export ANSIBLE_ROLES_PATH=$ANSIBLE_ROLES_PATH:$KAYOBE_PATH/ansible/roles
	export ANSIBLE_ROLES_PATH="$ANSIBLE_ROLES_PATH:$KAYOBE_PATH/ansible/roles"
	set +x
	fi
	if [[ -z "$ANSIBLE_ROLES_PATH" ]]; then
	ANSIBLE_ROLES_PATH_NEW="$KAYOBE_PATH/ansible/roles"
	else
	ANSIBLE_ROLES_PATH_NEW="$ANSIBLE_ROLES_PATH:$KAYOBE_PATH/ansible/roles"
	fi
	set -x
	export ANSIBLE_ROLES_PATH="$ANSIBLE_ROLES_PATH_NEW"
	set +x