Make daemonset mountPropagation configurable, remove bidirectional default

[jlubins]

This PR addresses issues #119 and #154 where the core-dump-handler causes excessive bind mounts due to bidirectional mount propagation. When pods restart frequently (e.g., due to memory limits being set too low), this has potential to create thousands of duplicate bind mounts, leading to:

• High I/O wait times
• Node performance degradation
• Potential node failures

The current implementation hardcodes mountPropagation: Bidirectional in the DaemonSet template. As noted in the Kubernetes documentation, bidirectional mount propagation can be dangerous and requires containers to properly clean up mounts on termination. Each pod restart doubles the number of mounts, quickly reaching system limits.

This PR makes mountPropagation configurable via Helm values and removes the bidirectional default. Users can now:

• Use the safer default (no mount propagation specified)
• Explicitly set bidirectional mode if needed for their use case
• Choose other propagation modes as appropriate