PDI-11363 - Database Lookup Step Performance Degraded in 5 vs 4.4.0.2

junit added
PDI-11363 - Database Lookup Step Performance Degraded in 5 vs 4.4.0.2

When using getLookup calls there is no need to make attempt to retrieve
row set metadata for every call. That may bring performance penalty
depends on jdbc driver implementation. For some drivers that penalty can
be huge (postgres).
During the execution calling getLookup() method we changing usually only
lookup where clause which will not impact return row structure.
Merge pull request #321 from prakapenka/PDI-11363

PDI-11363 - Database Lookup Step Performance Degraded in 5 vs 4.4.0.2