[Bug]: Container creation fails when pids.limit is set to 1

Bug Description

When linux.resources.pids.limit is set to 0 in config.json at container creation time, youki create fails with a fork error in the intermediate process. runc handles this case by writing pids.max=1 and successfully creating the container, but youki fails outright.

This was discovered in #3634.

Steps to Reproduce

1. Run youki spec to generate the default config.json.
2. Edit config.json so that it runs a long-lived process and sets pids.limit to 0:
   json复制

   {
     "process": {
       "args": [
         "sleep",
         "1000"
       ]
     },
     "linux": {
       "cgroupsPath": "/runtime-test/update_common_limits",
       "resources": {
         "pids": {
           "limit": 0
         }
       }
     }
   }

   all other fields left at the youki spec default.
3. Run youki create runtime-test.
4. Observe that container creation fails.

For comparison, runc succeeds under the same config and ends up with pids.max=1:

$ runc create runtime-test
$ cat /sys/fs/cgroup/runtime-test/update_common_limits/pids.max
1

youki fails with:

$ youki create runtime-test
ERROR libcontainer::process::container_intermediate_process: failed to fork init process: failed to clone process
ERROR libcontainer::process::container_main_process: failed to run intermediate process failed to launch init process
ERROR libcontainer::container::builder_impl: failed to run container process intermediate process error failed to launch init process
ERROR youki: error in executing command: failed to create container: intermediate process error failed to launch init process
Error: failed to create container: intermediate process error failed to launch init process

Expectation

youki should succeed when pids.limit is 0, matching runc's behavior of setting pids.max=1

System and Setup Info

No response

Additional Context

• Related PR: youki-dev/youki#3634
• Related issue: youki-dev/youki#3594