tests: fixup error asserts in init-data test

Guest components is less verbose with its error message now. This will
be fixed after the release, but for now, update the tests with the new
more general message.

Signed-off-by: Tobin Feldman-Fitzthum <tobin@ibm.com>

tests/integration/kubernetes/k8s-initdata.bats

@@ -165,7 +165,7 @@ EOF
     echo "Pod ${kata_pod}: $(cat ${kata_pod})"
 
     assert_pod_fail "${kata_pod}"
-    assert_logs_contain "${node}" kata "${node_start_time}" "image security validation failed"
+    assert_logs_contain "${node}" kata "${node_start_time}" "failed to pull image"
 }
 
 @test "Test that creating a container from an rejected image not configured by initdata, fails according to CDH error" {