Invocation of master_add_node() fails if citus wasn't created on a worker beforehand

### Description
Before `9.3.0` we used the following script to create a new database on an existing server:
```sql
CREATE DATABASE ;
SELECT run_command_on_workers($cmd$ CREATE DATABASE ; $cmd$);
\c
CREATE EXTENSION citus;
SELECT master_add_node('worker_1_ip', 5432);
SELECT master_add_node('worker_2_ip', 5432);
SELECT run_command_on_workers($cmd$ CREATE EXTENSION citus; $cmd$);
```

### Expected behavior
Database is created

### Actual behavior
With `9.3.0` `master_add_node` fails with
```
WARNING: function assign_distributed_transaction_id(integer, integer, unknown) does not exist
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
```