test/system: adjust pod memory limit for runc minimum requirement

runc requires a minimum of 6MB memory to start containers due to
security fixes that increased memory footprint. The test was using
5MB which works with crun but fails with runc, causing conmon to
crash and produce "readObjectStart: expect { or n, but found ,"
JSON parsing errors.

Detect the runtime and adjust memory limits accordingly:
- runc: 6MB minimum (6291456 bytes)
- crun: 5MB (5242880 bytes) - can run with less memory

This fixes the "pod resource limits" test failure when using runc
on RHEL 9.2.0 and other systems.

Signed-off-by: Lokesh Mandvekar <lsm5@redhat.com>

test/system/200-pod.bats

@@ -490,6 +490,14 @@ spec:
     skip_if_cgroupsv1 "resource limits only meaningful on cgroups V2"
     skip_if_aarch64 "FIXME: #15074 - flakes often on aarch64"
 
+    # runc requires minimum 6MB memory, crun can work with 5MB
+    local memory_limit="5m"
+    local memory_max_bytes="5242880"
+    if [[ $(podman_runtime) == "runc" ]]; then
+        memory_limit="6m"
+        memory_max_bytes="6291456"
+    fi
+
     # create loopback device
     lofile=${PODMAN_TMPDIR}/disk.img
     fallocate -l 1k  ${lofile}
@@ -508,7 +516,7 @@ spec:
     # FIXME: #15464: blkio-weight-device not working
     expected_limits="
 cpu.max         | 500000 100000
-memory.max      | 5242880
+memory.max      | $memory_max_bytes
 memory.swap.max | 1068498944
 io.bfq.weight   | default 50
 io.max          | $lomajmin rbps=1048576 wbps=1048576 riops=max wiops=max
@@ -516,7 +524,7 @@ io.max          | $lomajmin rbps=1048576 wbps=1048576 riops=max wiops=max
 
     for cgm in systemd cgroupfs; do
         local name=resources-$cgm
-        run_podman --cgroup-manager=$cgm pod create --name=$name --cpus=5 --memory=5m --memory-swap=1g --cpu-shares=1000 --cpuset-cpus=0 --cpuset-mems=0 --device-read-bps=${LOOPDEVICE}:1mb --device-write-bps=${LOOPDEVICE}:1mb --blkio-weight=50
+        run_podman --cgroup-manager=$cgm pod create --name=$name --cpus=5 --memory=$memory_limit --memory-swap=1g --cpu-shares=1000 --cpuset-cpus=0 --cpuset-mems=0 --device-read-bps=${LOOPDEVICE}:1mb --device-write-bps=${LOOPDEVICE}:1mb --blkio-weight=50
         run_podman --cgroup-manager=$cgm pod start $name
         run_podman pod inspect --format '{{.CgroupPath}}' $name
         local cgroup_path="$output"