test: bump the TEST-47 sleeps once again

Several recent failed runs show that the test is still racy in two ways:

1) Sometimes it takes a while before the PID file is created, leading
   to:

```
[   10.950540] testsuite-47.sh[308]: ++ cat /leakedtestpid
[   10.959712] testsuite-47.sh[308]: cat: /leakedtestpid: No such file or directory
[   10.959824] testsuite-47.sh[298]: + leaked_pid=
```

2) Again, sometimes we check the leaked PID before the unit is actually
   stopped, leading to a false negative:

```
[   18.099599] testsuite-47.sh[346]: ++ cat /leakedtestpid
[   18.116462] testsuite-47.sh[333]: + leaked_pid=342
[   18.117101] testsuite-47.sh[333]: + systemctl stop testsuite-47-repro
...
[   20.033907] testsuite-47.sh[333]: + ps -p 342
[   20.080050] testsuite-47.sh[351]:     PID TTY          TIME CMD
[   20.080050] testsuite-47.sh[351]:     342 ?        00:00:00 sleep
[   20.082040] testsuite-47.sh[333]: + exit 42
```