fix: revert GetBootTimeNs() to fix timestamp drift (#277)

Revert from commit bcd9064 when `GetBootTimeNs()` was in `internal/consumer/net.go` as `getBootTimeNs()`.

Timestamp drift appeared after the first capture: every real second elapsed would be like 2 seconds in the timestamp.
For example, with a `ping` command sending ICMP packets every second, the packets would have timestamps that were 2 seconds apart

Author: xav-jann1

internal/host/host.go

@@ -84,23 +84,12 @@ func GetKernelVersion() (string, error) {
 	return kernelVersionInfo.version, kernelVersionInfo.err
 }
 
-var bootTimeInfo struct {
-	once sync.Once
-	ts   int64
-	err  error
-}
-
 func GetBootTimeNs() (int64, error) {
-	bootTimeInfo.once.Do(func() {
-		var ts unix.Timespec
-		err := unix.ClockGettime(unix.CLOCK_MONOTONIC, &ts)
-		if err != nil {
-			bootTimeInfo.err = fmt.Errorf("could not get time: %w", err)
-		} else {
-
-			bootTimeInfo.ts = unix.TimespecToNsec(ts)
-		}
-	})
+	var ts unix.Timespec
+	err := unix.ClockGettime(unix.CLOCK_MONOTONIC, &ts)
+	if err != nil {
+		return 0, fmt.Errorf("could not get time: %w", err)
+	}
 
-	return bootTimeInfo.ts, bootTimeInfo.err
+	return unix.TimespecToNsec(ts), nil
 }