jdbc tests/test_no_7 query is not supported by Citus

[onurctirtir]

test_no_7 query from https://github.com/citusdata/test-automation/blob/jdbc/jdbc/JDBCReleaseTest.java#L121 is not supported by Citus. For this reason:

• We get some citus planner errors for append tables as below:

"ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns"   

(It is the expected behaviour as level-1 subquery does not join ""supplier"" table with other 3 tables on its distribution column, we should change the test query)

• We get some citus planner errors for hash dist. tables as below:

ERROR:  cannot perform distributed planning on this query
DETAIL:  Cartesian products are currently unsupported

(It is the expected behaviour as level-2 subquery does cartesian product, we should change the test query)