HPCC-9765 Fetching list of possible targets is slow

Switched from TpTargetClusterQuery function to TpLogicalClusterQuery.

Fixes HPCC-9765

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #4674 from GordonSmith/HPCC-9765

HPCC-9765 Fetching list of possible targets is slow

Reviewed-By: Kevin Wang <kevin.wang@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>