fix(ci): enable kube-linter default checks

[KeiaiLab-PHIL]

Summary

• Re-enable kube-linter default checks by removing doNotAutoAddDefaults: true and the empty include list.
• Keep exclude: [] so future exceptions are explicit.
• This prevents empty/invalid SARIF output while still surfacing chart findings through SARIF.

Validation

• helm lint charts/mongodb-operator
• kube-linter lint /tmp/mongodb-kube-linter-rendered --config .github/kube-linter-config.yaml --format plain now reports real PDB findings.
• kube-linter lint ... --format sarif --output /tmp/mongodb-kube-linter.sarif writes valid SARIF 2.1.0 with 6 results.

Notes

• The kube-linter workflow already uses continue-on-error: true for chart-level follow-up findings. The fix targets SARIF validity, not suppressing findings.