ctdb-tests: Simplify pstree output in eventd unit tests

ctdb-tests: Simplify pstree output in eventd unit tests

pstree truncates output when it exceeds a maximum width - the default
is 132 columns.  A couple of recent
commits (12fd8d7a5c5d14d403aac6cd9e318afcd0a8e159,
b23f3f996038626f618c5b5aa552686c1b852f44) lengthened the command
string in the output so that it is more likely to exceed this limit
and be truncated, as below:

==================================================
Running "cat /memdisk/autobuild/fl/b1851760/ctdb/ctdb/tests/var/eventd/debug_script.log"
--------------------------------------------------
Output (Exit status: 0):
--------------------------------------------------
02.enabled.scri,PID /memdisk/autobuild/fl/b1851760/ctdb/ctdb/tests/var/eventd/events/random/02.enabled.script ...
  `-sleep,PID 99
01.disabled          DISABLED
02.enabled           TIMEDOUT   DATETIME
  OUTPUT: Sleeping for 99 seconds
--------------------------------------------------
Required output (Exit status: 0):
--------------------------------------------------
02.enabled.scri,PID /memdisk/autobuild/fl/b1851760/ctdb/ctdb/tests/var/eventd/events/random/02.enabled.script verbosetimeout
  `-sleep,PID 99
01.disabled          DISABLED
02.enabled           TIMEDOUT   DATETIME
  OUTPUT: Sleeping for 99 seconds

FAILED

It isn't clear that the above example exceeds 132 characters, given
that the PID has been filtered into a fixed string, but it certainly
goes close.  Whether or not it is truncated probably depends on the
width of the PID in the unfiltered output.  This would explain why the
test flaps.

Avoid the output truncation by dropping the -a and -p options to
simplify the pstree output.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13531

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>