Total Processes in MiscStat Corrected

The `ProcsTotal` in the `MiscStat` structure was very inaccurate. It was reading
a value which is the total number of kernel scheduling entities. This includes
both processes and threads significantly overcounting.

This instead uses an existing method already in common to count the number of
processes via the /proc filesystem where any directory is a number. This should
still be a single syscall to read that directory entry.

This fixes #1606.

load/load_linux.go

@@ -107,7 +107,7 @@ func MiscWithContext(ctx context.Context) (*MiscStat, error) {
 
 	}
 
-	procsTotal, err := getProcsTotal(ctx)
+	procsTotal, err := common.NumProcsWithContext(ctx)
 	if err != nil {
 		return ret, err
 	}
@@ -116,14 +116,6 @@ func MiscWithContext(ctx context.Context) (*MiscStat, error) {
 	return ret, nil
 }
 
-func getProcsTotal(ctx context.Context) (int64, error) {
-	values, err := readLoadAvgFromFile(ctx)
-	if err != nil {
-		return 0, err
-	}
-	return strconv.ParseInt(strings.Split(values[3], "/")[1], 10, 64)
-}
-
 func readLoadAvgFromFile(ctx context.Context) ([]string, error) {
 	loadavgFilename := common.HostProcWithContext(ctx, "loadavg")
 	line, err := os.ReadFile(loadavgFilename)