test: bump the `reattach` timeout when running w/ plain QEMU

test: bump the `reattach` timeout when running w/ plain QEMU

As it might sometimes take slightly longer without the acceleration:

```
[  176.805681] testsuite-29.sh[534]: + cp /usr/share/app1.raw /tmp/app1_2.raw
[  176.885365] testsuite-29.sh[534]: + timeout 30 portablectl reattach --now --runtime --extension /tmp/app1_2.raw /usr/share/minimal_1.raw app1
[  177.053358] portablectl[993]: (Matching unit files with prefixes 'app1'.)
[  177.138770] kernel: loop0: detected capacity change from 0 to 2965504
[  177.343137] kernel: loop1: detected capacity change from 0 to 4096
...
[  201.932062] systemd[1]: app1.service: Deactivated successfully.
[  202.009310] systemd[1]: Stopped app1.service.
[  202.053776] systemd[1]: app1.service: Consumed 2.183s CPU time.
[  202.125061] systemd[1]: Stopping app1.service...
[  202.611760] systemd[1]: Starting modprobe@dm_mod.service...
[  202.851031] systemd[1]: Starting modprobe@dm_verity.service...
[  202.909352] systemd[1]: Starting modprobe@loop.service...
[  203.198918] systemd[1]: Starting app1.service...
[  207.145494] kernel: audit: type=1130 audit(1663770336.105:428): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=kernel msg='unit=testsuite-29 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed'
[  207.652545] systemd[1]: testsuite-29.service: Main process exited, code=exited, status=124/n/a
[  207.665088] systemd[1]: testsuite-29.service: Failed with result 'exit-code'.
[  207.830522] systemd[1]: Failed to start testsuite-29.service.
...
[  208.889449] script1.sh[1035]: ID="centos"
[  208.889449] script1.sh[1035]: VERSION_ID="8"
[  208.889449] script1.sh[1035]: SYSEXT_SCOPE=portable
[  208.889449] script1.sh[1035]: PORTABLE_PREFIXES=app1
...
[  214.155097] systemd[1]: app1.service: Deactivated successfully.
```

Spotted in Ubuntu CI and CentOS CI.

Follow-up to 706c9a30ac.