bootstrap: Increase podman pids_limit to 4096 (#3611)

The nightly build jobs have been failing[1] due to default podman
pids_limit (2048)[2] in the bootstrap image being too low.

Increasing this to 4096 allows the nightly build jobs to complete
successfully[3].

[1] https://prow.ci.kubevirt.io/view/gs/kubevirt-prow/logs/periodic-kubevirt-push-nightly-build-main/1828599108043018240
[2] https://docs.podman.io/en/v5.2.2/markdown/podman-update.1.html#pids-limit-limit
[3] https://prow.ci.kubevirt.io/view/gs/kubevirt-prow/logs/periodic-kubevirt-push-nightly-build-main/1828835977469104128

Signed-off-by: Brian Carey <bcarey@redhat.com>

images/bootstrap/containers.conf

@@ -3,6 +3,7 @@ netns="private"
 userns="host"
 ipcns="host"
 cgroupns="host"
+pids_limit=4096
 log_driver = "k8s-file"
 [engine]
 cgroup_manager = "cgroupfs"