fix(ibmcloud): remove PID limits to prevent EAGAIN during heavy builds

[adrianriobo]

Problem

On ppc64le (and s390x) runners, building wheel packages fails with:

```
ccache: error: Failed to fork: Resource temporarily unavailable
gcc: error: posix_spawn: Operation not permitted
```

Root cause: Pillow compiles 60+ C extension files. Each file spawns a
`ccache → gcc → cc1 → as` process chain (4 processes per file). Running
two concurrent jobs exhausts the container's cgroup `pids.max`, which
Podman inherits from the system default (~2048 on RHEL 9).

Three enforcement layers were all unset, each independently capable of
triggering the failure:

Layer	Before	After
Podman `pids_limit` in `containers.conf`	system default	`-1` (unlimited)
Docker executor `--docker-pids-limit`	not set (inherits Podman default)	`-1` (unlimited)
Systemd `TasksMax` on `gitlab-runner.service`	systemd default (512–4096)	`infinity`

Changes

• `pkg/integrations/gitlab/snippet-linux.sh`: adds a `pids_limit = -1`
  block in `/etc/containers/containers.conf` (idempotent, covers all DNS
  code-path branches); adds `--docker-pids-limit -1` to `gitlab-runner register`
  so the Docker executor explicitly removes the pids cgroup on each job container.
• `pkg/provider/ibmcloud/action/ibm-power/cloud-config`: adds
  `TasksMax=infinity` to the `gitlab-runner.service.d` drop-in.
• `pkg/provider/ibmcloud/action/ibm-z/cloud-config`: same fix applied to
  IBM Z runners to prevent the same failure class on s390x.

Test plan

• Re-provision a ppc64le runner with these changes and trigger a Pillow wheel build
• Confirm no EAGAIN / posix_spawn errors during C extension compilation
• Verify s390x runner is unaffected (TasksMax=infinity is a no-op on non-constrained hosts)

🤖 Generated with Claude Code

[coderabbitai]

📝 Walkthrough

Walkthrough

Configuration changes remove container PID limits and systemd task limits for GitLab runners. The GitLab integration script updates Podman and Docker runner settings, while IBM Power and IBM Z templates set TasksMax=infinity for the runner service.

Changes

PID and Task Limit Removal

Layer / File(s)	Summary
Container PID limit configuration pkg/integrations/gitlab/snippet-linux.sh	Ensures Podman uses pids_limit = -1 in the [containers] section and inserts the same setting into the Docker executor configuration.
Systemd TasksMax override pkg/provider/ibmcloud/action/ibm-power/cloud-config, pkg/provider/ibmcloud/action/ibm-z/cloud-config	Adds TasksMax=infinity to the GitLab runner systemd service override on IBM Power and IBM Z.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly describes removing PID limits to fix EAGAIN issues during heavy builds.
Description check	✅ Passed	The description matches the PR by explaining the PID-limit failures and the container, runner, and systemd changes.

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[Xaenalt]

So far, PID issue has not resurfaced, thanks!