hash partitioned table has overlapping shards in regression tests

Randomly got this test output
```
--- /home/marco/citus-fixseq/src/test/regress/expected/multi_prepare_plsql.out.modified 2020-09-29 19:00:04.630000000 +0200
+++ /home/marco/citus-fixseq/src/test/regress/results/multi_prepare_plsql.out.modified 2020-09-29 19:00:04.650000000 +0200
@@ -1100,25 +1100,21 @@
DROP TABLE execute_parameter_test;
-- check whether we can handle parameters + default
CREATE TABLE func_parameter_test (
key text NOT NULL,
seq int4 NOT NULL,
created_at timestamptz NOT NULL DEFAULT now(),
updated_at timestamptz NOT NULL DEFAULT now(),
PRIMARY KEY (key, seq)
);
SELECT create_distributed_table('func_parameter_test', 'key');
- create_distributed_table
----------------------------------------------------------------------
-
-(1 row)
-
+ERROR: hash partitioned table has overlapping shards
```