(DOCS-8782): Remove 'heap_usage_bytes' from server status output (#2198)

Author: jeff-allen-mongo

source/reference/command/serverStatus.txt

@@ -693,7 +693,6 @@ extra_info
 
    "extra_info" : {
       "note" : "fields vary by platform.",
-      "heap_usage_bytes" : <num>,
       "page_faults" : <num>
    },
 
@@ -706,11 +705,6 @@ extra_info
 
    A string with the text ``"fields vary by platform."``
 
-.. serverstatus:: extra_info.heap_usage_bytes
-
-   The total size in bytes of heap space used by the database process.
-   Available on Unix/Linux systems only.
-
 .. serverstatus:: extra_info.page_faults
 
    The total number of page faults. The