Fix integration test

Summary: The host may not have io controller enabled and thus may not have IO stats. Let's use memory pressure since exists even without any controller.

Reviewed By: brianc118

Differential Revision: D55880562

fbshipit-source-id: b416a90eb5324f2f526d26f652cd4f1f6c40cf96

below/src/test.rs

@@ -97,12 +97,12 @@ fn record_replay_integration() {
     restored_sample
         .cgroup
         .data
-        .io_total
+        .pressure
         .as_ref()
-        .expect("missing io.stat")
-        .rbytes_per_sec
+        .expect("missing memory.pressure")
+        .memory_full_pct
         .as_ref()
-        .expect("missing io stat read bytes per second");
+        .expect("missing memory.pressure.total");
     assert!(restored_sample.process.processes.len() == nr_procs);
     assert!(restored_sample.system.hostname == hostname);
     assert!(