Optimize dig parameters to decrease test run time

Optimize dig parameters to decrease test run time

Performing server setup checks using "+tries=3 +time=5" is redundant as
a single query is arguably good enough for determining whether a given
named instance was set up properly.  Only use multiple queries with a
long timeout for resolution checks in the "legacy" system test, in order
to significantly reduce its run time (on a contemporary machine, from
about 1m45s to 0m40s).

(cherry picked from commit 47b850348cbc2961bc44eb31c05cd620e5fc35f0)