test: workaround the failed error

Add workaround to fix error
```
content: error: Installing to filesystem: Gathering source info from container env: Subprocess failed: ExitStatus(unix_wait_status(256))
content: error: readdir: Too many open files
```

Signed-off-by: Huijing Hei <hhei@redhat.com>

Author: HuijingHei

tmt/tests/examples/test-on-ostree/test-install-on-ostree.sh

@@ -31,14 +31,16 @@ if [ "$TMT_REBOOT_COUNT" -eq 0 ]; then
     stateroot=$(bootc status --json | jq -r .status.booted.ostree.stateroot)
 
     # Need bind mount for /run/host-container-storage
-    podman run --rm --privileged \
+    podman run \
+        --rm --privileged \
         -v /dev:/dev \
+        -v /var/lib/containers:/var/lib/containers \
         -v /run/host-container-storage:/run/host-container-storage:ro \
         -v /:/target \
         --pid=host \
         --security-opt label=type:unconfined_t \
         ${BOOTC_target} \
-            env BOOTC_BOOTLOADER_DEBUG=1 STORAGE_OPTS=additionalimagestore=/run/host-container-storage \
+            env STORAGE_OPTS=additionalimagestore=/run/host-container-storage \
             bootc install to-existing-root \
             --stateroot=${stateroot} \
             --skip-fetch-check \