fix: add auditd config existence checks to linux security policy

[tas50]

Summary

• Adds file("/etc/audit/auditd.conf").exists precondition to all auditd rule checks in the Linux security policy
• Prevents confusing errors on systems where auditd is not installed

Test plan

• Run cnspec policy lint content/mondoo-linux-security.mql.yaml
• Verify checks pass on systems with auditd installed
• Verify checks gracefully handle systems without auditd

🤖 Generated with Claude Code

[mondoo-code-review]

Adds auditd config existence checks as preconditions to audit policy queries; looks correct and consistent.

[mondoo-code-review]

Straightforward addition of auditd config existence checks; no bugs or security issues found.

[github-actions]

Test Results

  1 files  ±0   38 suites  ±0   1m 16s ⏱️ -16s
709 tests ±0  708 ✅ ±0  1 💤 ±0  0 ❌ ±0 
710 runs  ±0  709 ✅ ±0  1 💤 ±0  0 ❌ ±0 

Results for commit 229a22b. ± Comparison against base commit 7f9a92a.

♻️ This comment has been updated with latest results.

[mondoo-code-review]

Test assertions relaxed to handle Kubernetes namespace auto-discovery producing multiple reports.

[mondoo-code-review]

Adds auditd config existence pre-checks to Linux security policy queries, preventing errors on systems without auditd installed.