add /proc to the sandbox to allow jvm to clear stack #56

Job	Run time
Security: Filesystem Isolation (File Privacy)	1m 11s
Resource: Fork Bomb Containment	1m 24s
Resilience: I/O Flood (Bounded Stderr)	1m 22s
Security: Memory Limit (Hard OOM)	1m 16s
Resilience: Inode Exhaustion Safety	1m 21s
Resilience: Orphan Grandchild Reaping	1m 9s
Security: Disk Cleanup (Storage Exhaustion)	1m 15s
Resilience: Signal Trap Uses SIGKILL Timeout	1m 20s
Resilience: Privileged Syscall Denial	1m 19s
Security: Network Namespace (Localhost Bridge)	1m 9s
	12m 46s

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