Option to ignore coredump exit codes from the sandboxed container init process

### Description

We've been getting spurious coredumps from our sandboxed containers that have had no panic trace from gVisor itself. After digging into a bunch of them, I've noticed that the applications inside the container are panicking or otherwise exiting with SIGSEGV/SIGABRT signals, which the sandbox is returning as it's own exit code. This causes systemd-coredump (or whatever `/proc/sys/kernel/core_pattern` is configured to do) to try and process a coredump event with no data, because there was no coredump generated by the sandbox process on the host.

Is there any point to gVisor exiting with signals that indicate a coredump? From `man 7 signals`, this set includes
- SIGABRT
- SIGBUS
- SIGFPE
- SIGILL
- SIGIOT (alias for SIGABRT)
- SIGQUIT
- SIGSEGV
- SIGSYS
- SIGTRAP
- SIGXCPU

If there's no core to be generated, this just causes noise since I don't believe systemd-coredumpd can be configured to ignore empty coredumps currently.

### Is this feature related to a specific bug?

_No response_

### Do you have a specific solution in mind?

_No response_