Fix package tool errors and KillUserProcesses setup on Azure Linux/Mariner

[umfranci]

Description

Fixes two issues that hit Azure Linux / CBL-Mariner nodes during package operations:

1. _dnf_tool AttributeError — _dnf_tool_name was only declared as a type
   annotation and never assigned a default. Any code path that called _dnf_tool()
   before the install path ran (e.g. _update_packages, clean_package_cache,
   repolist) crashed with an AttributeError. Now _dnf_tool_name is initialized
   to "" and resolved lazily inside _dnf_tool() (dnf if present, otherwise
   tdnf -q), with the result cached. Detection happens directly here instead of
   calling _initialize_package_installation(), which avoids an unintended
   systemd-logind restart and a possible recursion.

2. set_kill_user_processes failed on Azure Linux 4.0 — the code appended
   KillUserProcesses=no to /etc/systemd/logind.conf with sed, but on Azure
   Linux 4.0 that file doesn't exist by default, so the append failed and the
   setting was never applied. Now the setting is always written as a systemd
   drop-in (/etc/systemd/logind.conf.d/99-lisa-kill-user-processes.conf) with its
   own [Login] header. Drop-ins work uniformly across all Mariner/Azure Linux
   versions (even when the base file is missing), the file is rewritten each time so
   the operation is idempotent, and writes now fail loudly instead of being silently
   ignored.

Related Issue

Type of Change

• Bug fix
• New feature
• Breaking change
• Refactoring
• Documentation update

Checklist

• Description is filled in above
• No credentials, secrets, or internal details are included
• Peer review requested (if not, add required peer reviewers after raising PR)
• Tests executed and results posted below

Test Validation

Key Test Cases:
verify_os_update|verify_repository_installed

Impacted LISA Features:
CBLMariner (operating_system) - package install/update and KillUserProcesses setup

Tested Azure Marketplace Images:

• microsoftcblmariner cbl-mariner 2-gen2 latest
• microsoftcblmariner azurelinux-3 3-gen2 latest
• Azure Linux 4.0 image

Test Results

Image	VM Size	Result
microsoftcblmariner cbl-mariner 2-gen2 latest	Standard_D2s_v5	PASSED
microsoftcblmariner azurelinux-3 3-gen2 latest	Standard_D2s_v5	PASSED
Azure Linux 4.0 image	Standard_D2s_v5	PASSED

[Copilot]

Pull request overview

This PR fixes Azure Linux/CBL-Mariner package-management reliability by (1) preventing _dnf_tool() from crashing when called before the install path initializes the package tool and (2) making KillUserProcesses=no configuration robust on distros where /etc/systemd/logind.conf may not exist.

Changes:

• Initialize _dnf_tool_name with a default value and lazily resolve/cache dnf vs tdnf inside _dnf_tool().
• Write KillUserProcesses=no via a systemd logind drop-in (/etc/systemd/logind.conf.d/...) instead of editing /etc/systemd/logind.conf directly.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.