fix: add SCC to dag processor

[kesem0811]

helm: Add SCC role binding for dag-processor service account
Currently, the Airflow Helm chart includes a template that creates SCC (Security Context Constraints) role bindings for the service accounts of all components—except the dag-processor.

This PR adds an SCC role binding for the dag-processor service account to ensure consistent security configuration across all Airflow components.

This change is required in environments that use the dag-processor component together with SCC policies, such as OpenShift or other restricted Kubernetes clusters. Without this binding, the dag-processor may fail to start due to insufficient security privileges.

[boring-cyborg]

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[jedcunningham]

Thanks for the PR @kesem0811. Can you add test coverage here? (There might be more places in that file as well)

[eladkal]

Needs rebase