metric-config: remove the buffer/cache-memory threshold

The kernel will naturally attempt to use almost all free memory up with
buffers and caches.  We should not have a threshold on this behavior
by default.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic40a260667e89d62820e99753efda025ba5bde47
diff --git a/health_metric_config.cpp b/health_metric_config.cpp
index 68cb0cd..8a2d5e7 100644
--- a/health_metric_config.cpp
+++ b/health_metric_config.cpp
@@ -249,14 +249,7 @@
     },
     "Memory_Buffered_And_Cached": {
         "Frequency": 1,
-        "Window_size": 120,
-        "Threshold": {
-            "Critical_Upper": {
-                "Value": 85.0,
-                "Log": true,
-                "Target": ""
-            }
-        }
+        "Window_size": 120
     },
     "Storage_RW": {
         "Path": "/run/initramfs/rw",