test: add a test for /etc/resolv.conf in rw/ro mode

This patch isn't adding a test for /etc/hosts as that requires host
network and we don't want to play with host's /etc/hosts when running
make localintegration on our laptops. That may change in the future
moving to some sort of in-container testing.

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

test/testdata/container_config.json

@@ -38,7 +38,6 @@
 		"daemon": "crio"
 	},
 	"privileged": true,
-	"readonly_rootfs": true,
 	"log_path": "",
 	"stdin": false,
 	"stdin_once": false,
@@ -51,6 +50,7 @@
 			"oom_score_adj": 30
 		},
 		"security_context": {
+			"readonly_rootfs": false,
 			"capabilities": {
 				"add_capabilities": [
 					"setuid",