ctdb-tests: Make process exists test more resilient

ctdb-tests: Make process exists test more resilient

This can fail as follows:

--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--
Running test ./tests/UNIT/tool/ctdb.process-exists.003.sh (02:26:30)
--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--
ctdb.process-exists.003      - ctdbd process with multiple connections on node 0
Setting up fake ctdbd
<10||0|
OK
<10|PID 26107 exists
|0|
OK
==================================================
Running "ctdb -d NOTICE process-exists 26107 0x1234567812345678"
PASSED
==================================================
Running "ctdb -d NOTICE process-exists 26107 0xaebbccdd12345678"
Registered SRVID 0xaebbccdd12345678
--------------------------------------------------
Output (Exit status: 1):
--------------------------------------------------
PID 26107 with SRVID 0xaebbccdd12345678 does not exist
--------------------------------------------------
Required output (Exit status: 0):
--------------------------------------------------
PID 26107 with SRVID 0xaebbccdd12345678 exists

FAILED
connection to daemon closed, exiting
==========================================================================
TEST FAILED: ./tests/UNIT/tool/ctdb.process-exists.003.sh (status 1) (duration: 0s)
==========================================================================

This happens when dummy_client has not registered the SRVID (for its
10th connection) before the 2nd simple_test.

Change the initial wait to ensure that the SRVID is registered.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
Autobuild-User(master): Amitay Isaacs <amitay@samba.org>
Autobuild-Date(master): Wed Nov  6 02:46:24 UTC 2019 on sn-devel-184